Frequently asked questions.
Plain-English answers to the questions UK company directors ask us most. Can't find what you need? Contact support and we respond within one working day.
Second CT600 when the first return is already filed
Can I submit only the second CT600 if the first return is already filed?
Yes. File the outstanding short period as a separate original return using its own dates. You do not need to resubmit the first return just to complete the second. Choose software that supports filing only the outstanding period.
Do I attach accounts to the second CT600 if they were attached to the first?
An accounts-already-supplied route can apply when the first return included the full accounts covering both tax periods. The second return must explain why accounts are omitted. Active companies include their computation. Dormant returns use the reason “Company dormant” for omitting computations. This is not a general exemption from supplying accounts.
Do I need a second short-period CT600 if the company made a loss?
Yes, if HMRC requires a return for that period. Making a loss or having no Corporation Tax to pay does not remove the requirement to file. Use the short period figures and applicable tax adjustments.
Should I amend the first CT600 to cover the whole 13-month accounts period?
No. A Corporation Tax accounting period cannot exceed 12 months. File the outstanding second period separately. An amendment to the first return is for correcting that return, not for extending it to cover both periods.
Can a dormant company file only the second short-period CT600?
Yes, if HMRC requires the remaining return and the first CT600 included the full accounts. Select Dormant as the trading status and File only the remaining CT600 as the filing purpose. The first return is not resubmitted. Accounts are omitted because they were supplied with the first return, and computations are omitted using the reason Company dormant.
Can I use different software to file my second CT600?
Choose software such as SimpleCompanyTax to file only the second CT600 when the first was filed elsewhere. For eligible companies, our remaining-return option uses the short-period dates and handles accounts already supplied with the first return.
CT600 tax already paid and partial payments
Do I still need to file a CT600 if I have already paid Corporation Tax?
Yes. Paying the tax does not deliver a Company Tax Return. If HMRC has issued a notice to file, address that obligation even if nothing remains to pay. Payment and filing have separate deadlines.
Where do I enter tax already paid on a CT600?
Use box 595 for Corporation Tax paid for the return’s accounting period and not already repaid by HMRC. It is different from the tax liability and the balance still outstanding.
Can I file a CT600 with only part of the Corporation Tax paid?
Yes. Enter the relevant amount already paid in box 595 and report the full tax liability. The reconciliation calculates the balance still to pay. Filing does not extend the payment deadline or arrange a payment plan.
What should box 600 show if I have paid all the Corporation Tax?
For an ordinary return with no other credits, a payment equal to the tax liability leaves zero outstanding. For example, £3,800 liability and £3,800 in box 595 leave £0 in box 600. Check the HMRC account for later payments, interest or other charges.
Do I subtract HMRC refunds from tax already paid in box 595?
Yes. Exclude amounts already repaid by HMRC. For example, £2,000 paid for the period with £300 already refunded leaves £1,700 not repaid. Keep a reconciliation of the payments and refunds.
Can I include VAT, PAYE or next year’s Corporation Tax in box 595?
No. Box 595 is for Corporation Tax paid for the return’s accounting period. Do not include payments for other taxes or periods, restitution tax or coronavirus support scheme overpayments. Check an uncertain allocation with HMRC.
How do I enter tax already paid when there are two CT600 returns?
Identify the payment belonging to each return and enter each amount separately. Do not divide payments by days or repeat the whole payment on both returns. In SimpleCompanyTax, click + 595 Corporation Tax already paid under Tax adjustments. Enter each payment in 595 Corporation Tax already paid under Return 1 or Return 2, checking the dates shown.
What happens if tax already paid is more than the Corporation Tax bill?
For an ordinary return with no other credits, the excess is tax overpaid in box 605. A £4,000 payment against £3,800 liability gives £200 overpaid. Do not enter a negative box 600. A repayment is handled by HMRC and is not guaranteed to arrive immediately.
Can I enter Corporation Tax already paid in pounds and pence?
Yes. SimpleCompanyTax accepts payment amounts to two decimal places. For example, enter £2,000.25 as 2000.25. Keep the payment separate from whole-pound accounts inputs, and use the amount supported by the payment records.
Does entering box 595 pay HMRC or check my payments automatically?
No. Box 595 records the payment figure you provide. SimpleCompanyTax does not fetch your HMRC statement or make a tax payment through this field. Check your records and HMRC account, then confirm the figures and pay any remaining bill separately.
CT600 rounding and decimal places
How should I round figures for my CT600 filing?
Follow the instructions for the field and software. Where nearest-pound figures are requested, total each category first. For positive amounts, below 50p rounds down and 50p or above rounds up, so £1.49 becomes £1 and £1.50 becomes £2. SimpleCompanyTax uses this convention for its whole-pound financial inputs. Keep pence in the underlying records.
Does HMRC say to round CT600 turnover to the nearest pound?
The CT600 schema specifies a whole-pound format for turnover, but that format does not prescribe rounding up, down or at 50p. Do not describe the schema as an HMRC instruction to round turnover to the nearest pound. Follow the relevant field instructions and reconcile your accounts and computation.
Does FRS 105 specify a 50p rounding rule?
No. Paragraph 3.13(d) requires the rounding level to be shown in the financial statements. Paragraphs 8.4 and 8.6 address policy judgement and consistency. They do not prescribe a 50p CT600 rounding threshold or establish an ACCA-approved rounding algorithm.
Is Corporation Tax rounded to the nearest pound?
Tax amounts can include pence. SimpleCompanyTax uses nearest-penny rounding for calculated tax and marginal-relief amounts, producing two decimal places, with whole-pound return fields formatted separately. Rounding can happen to components before the final total, so it is not simply a whole-pound rounding of the final tax bill.
Why is my CT600 tax slightly different from Excel?
Excel can display whole pounds while still calculating with hidden pence. Compare the actual input values, tax adjustments, periods and rounding of individual tax components. A small difference may be caused by rounding, but a difference below £1 is not automatically harmless. Investigate an unexplained difference before filing.
Different CT600 and Companies House dates
Can my CT600 dates be different from my Companies House accounts?
Yes. The tax period and the annual accounts period can differ, for example after a dormant company starts trading or where one set of accounts covers two tax periods. Use the dates that follow from your actual tax position. Do not choose shorter dates just to leave out profit.
Can a Corporation Tax period end before the Companies House accounts end?
Yes, an event such as stopping a trade can end a tax period before the accounts year end. You must still check whether the company remains within Corporation Tax and needs another return. For supported HMRC-only filings, SimpleCompanyTax accepts an earlier end within the accounts period and tells you which dates the entered figures must cover.
Do I need to change my company year end to use different CT600 dates?
No, not just because the tax period legitimately differs. Keep the actual annual accounts period. If you want to change the annual accounts year end itself, use the Companies House process and address the resulting HMRC dates separately.
What should I do if the accounting period on my HMRC notice is wrong?
Compare the notice with your HMRC online account, accounts dates and activity records, then contact HMRC about the discrepancy. Explain the dates shown, the dates you believe apply and why. A software date edit does not itself correct a notice or cancel a filing obligation.
Where do I enter a different tax start or end in SimpleCompanyTax?
In step 1, choose HMRC CT600 under What are you filing, enter the full Companies House accounts dates, then tick My HMRC Corporation Tax period is different from my statutory accounts period. Enter both tax dates and complete the two confirmations. The selected tax span must fit within the accounts period.
Does choosing a shorter tax period automatically reduce the figures I entered?
No. In the separate-period workflow we use the entered income, expenses and tax amounts for the selected tax span in full. The annual accounts must still be complete, and balance-sheet figures remain at the statutory accounts end. Existing short-period limits and calculations within the selected tax span still apply.
Why is the different Corporation Tax period checkbox missing?
Check that you selected HMRC CT600 only. The separate-period option is not offered for Companies House only or combined filings. If you need to file annual accounts at Companies House, arrange that filing separately. Do not change valid tax dates just to enable a combined filing.
Does an earlier CT600 end change my payment and filing deadlines?
Check them separately. For companies outside instalment payments, the normal payment deadline is nine months and one day after the tax period ends. The return filing deadline also takes account of the relevant accounts period and the notice to file. Do not shift both deadlines by the same number of months.
Accounts and computation details
Is the micro-entity turnover limit reduced for short accounts?
Yes. The turnover ceiling is adjusted for the accounts-period length. Under the limits applying from 6 April 2025, a six-month period has a £500,000 ceiling. Asset and employee limits are not proportionately reduced. The full qualification rules still apply.
Do I lose micro-entity status after one year above the limits?
Not necessarily. In later years a change in meeting the size conditions affects qualification only after two consecutive years. The first financial year has its own rule, and exclusions and the April 2025 transition also matter. A current-year comparison alone does not decide qualification.
Where do I put individual disposal calculations for my company?
Paste them into Disposal calculations under Tax adjustments. HMRC requires individual workings, including relevant claims or elections, when boxes 210, 215 or 825 are completed. We attach your text without recalculating it. There is one field per return. You can continue with it blank, but a return requiring the workings is incomplete without them.
Are current creditors the same as trade payables?
No. Current creditors can include suppliers, tax and director loans due within one year. Enter the aggregate once. We tag it as current creditors without requiring a supplier breakdown.
Why ask whether a dormant company has traded before?
Dormant this year and never traded are different accounts classifications. For a new dormant draft we use your answer to select the right classification, without evidence checks. We do not ask when its first period starts on incorporation. Existing drafts keep their saved behaviour.
Does the first-year allowance breakdown give another tax deduction?
No. It explains the first-year amount already included in total capital allowances. A £3,500 total including £500 of first-year allowance still gives a £3,500 deduction, not £4,000.
Director's loan waivers
Where do I enter a full or partial director loan write-off?
In Step 2, open Tax adjustments and add a director’s loan waiver. Enter the amount legally released, effective date and tax treatment. Enter the balance still owed in Creditors: due within one year or Creditors: due after more than one year, splitting it if necessary. We generate the accounts and Corporation Tax return automatically, including two returns for a long accounting period. The supported route is a taxable profit-and-loss gain on an ordinary cash loan. Other accounting or tax treatments need a different calculation which we do not yet support.
Does a director’s loan waiver go in Other income or CT600 box 205?
No. Enter it once using Director’s loan waiver under Tax adjustments, not Other income. A trading amount is included in boxes 155 and 165. A non-trading amount enters the loan relationship calculation, whose net profit may appear in box 170. Box 205 is only for income not included under another CT600 heading, so using it would count the waiver twice.
Where can I find official guidance on director loan waivers and the CT600?
For a loan owed by the company to its director, read these official HMRC sources. They are useful whichever filing software you use.
Capital losses, dividends and AIA
What allowance does the automatic capital loss calculation assume?
When no company allowance is stated, it assumes the maximum for the period. This is not a check of your entitlement. Use your own calculated relief if your allowance is lower, even below £5 million.
Can I use a manual capital claim with other restricted losses?
Not every mixed-loss case is supported. If other brought-forward relief is used and the shared allowance restriction applies, the return can still be blocked because the service does not collect a restricted deduction for every other stream. Your manual capital claim does not override that limitation.
What is a brought-forward capital loss?
Can capital losses reduce trading profit?
Is the opening capital loss balance the amount I can deduct?
When does the brought-forward capital loss restriction apply?
Does every company have a £5 million capital loss allowance?
Can I file using my own calculated capital loss relief?
What happens to unused capital losses?
How do I enter capital losses when filing two CT600 returns?
What if I do not know my brought-forward capital loss balance?
Does a blank capital loss relief entry mean zero?
Can a six-month AIA claim use a monthly calculation?
Are all UK dividends received by a company exempt?
Can I deduct foreign tax credits from the taxable dividend field?
Non-trading loan relationship deficits
Where do I input my Brought Forward Non-trading Loan Relationship Deficit?
Open Step 2 of your filing, go to Tax adjustments and enter the unused qualifying balance in “Non-trading loan relationship deficits brought forward”. Review the claim directly underneath it. Do not put it in trading losses brought forward or add it to this year’s interest expense.
What is a non-trading loan relationship deficit?
It is a tax loss arising when allowable non-trading loan relationship debits exceed taxable non-trading loan relationship credits. It is separate from a trading or property loss and is not the outstanding loan balance. Non-trading mortgage interest in a property company is one possible source.
Can I choose how much brought-forward non-trading deficit to claim?
Yes, for the eligible total-profits claims this feature supports. Leave the claim blank to use the calculated maximum, enter a smaller amount to claim less, or enter 0 to make no claim on that return. The opening balance is not itself the claim. Review the deductions allowance as well.
How do I enter a brought-forward loan deficit for accounts longer than 12 months?
Enter the opening balance once. The inline splitter below the field shows the two Corporation Tax returns, with a separate claim and deductions allowance for each. The first return’s unused balance carries into the second. The balance is not day-apportioned and the two claims do not have to use it all.
Why is my maximum claim £0 when a balance remains?
Your non-trading deficit balance is what remains available, not what you can necessarily use on this return. In a completed calculation, a £0 maximum with a positive balance means there are no profits left against which to claim that brought-forward deficit after other reliefs. The unused eligible balance carries forward. For example, Return 2 can show £90,000 available but a £0 maximum claim. Check the calculation and resolve any validation messages before relying on the figure.
What happens if I claim zero in both returns?
Entering 0 in both non-trading deficit claim fields means neither return uses your brought-forward balance. If you start with £90,000, that existing balance remains £90,000 to carry forward beyond Return 2, assuming no other changes to it. Neither return receives a tax reduction from that balance. Future use remains subject to eligibility and available profits. Enter an explicit 0 in each claim field because leaving a field blank uses our calculated maximum instead.
Which CT600 box is used for a brought-forward non-trading loan deficit?
Box 263 records an eligible brought-forward deficit claimed against total profits. Box 260 is for current-period deficit relief, while box 795 reports the deficit arising in the return. Restricted brought-forward deficits using box 230 are not supported by this feature.
Getting started
Do I need an accountant to file my company tax?
Not necessarily. A director can file a straightforward micro-entity CT600 and accounts using suitable software. Use an accountant if the company has complex transactions, group relief, R&D claims or anything outside our supported scope, or if you are not confident about the tax treatment. Associated companies are fine: you enter how many and we divide the Corporation Tax limits for you.
What is "company tax" in the UK?
When people say "company tax," they usually mean corporation tax, the tax UK limited companies pay on their profits. Your company files a corporation tax return (CT600) to HMRC after each accounting period, reporting its income, expenses, and the tax owed. Corporation tax is charged at 19–25% depending on the profit level.
What is a CT600?
A CT600 is the Company Tax Return used to report a company's taxable profit or loss and Corporation Tax to HMRC. Most returns are filed online with iXBRL accounts and a tax computation. A company must file when HMRC issues a notice to deliver a return, even if it made a loss or owes no tax. A company HMRC has confirmed as dormant usually does not file again unless HMRC sends another notice.
What if my company made no money?
You still need annual accounts for Companies House, and you must file a Company Tax Return if HMRC has sent a notice to deliver one. No taxable profit normally means no Corporation Tax, but the filing deadlines still apply. If the company is genuinely dormant, tell HMRC so it does not keep requesting returns.
What is the difference between a CT600, annual accounts and a confirmation statement?
They are separate filings. The CT600 reports Corporation Tax to HMRC. Annual accounts go to Companies House. A confirmation statement updates the company details Companies House holds. SimpleCompanyTax files the CT600 and annual accounts, but not confirmation statements.
What if my company is dormant?
Dormant companies still file annual accounts and a confirmation statement with Companies House. If HMRC has issued a notice to deliver a Company Tax Return for the period, file that return and tell HMRC the company is dormant. HMRC normally stops requesting later returns until the company becomes active again.
HMRC asked me to file a return where the start and end date are the same day. Is that right?
Yes. A one-day "stub" return can arise when a company is incorporated on the last day of a month, because HMRC limits a Corporation Tax period to 12 months. Enter the same date in both period fields. The stub goes to HMRC only and does not replace the longer Companies House accounts period.
Do my annual accounts and my Corporation Tax return have to cover the same dates?
Usually they do, but not always. If your company was dormant and then started trading, your annual accounts can cover the whole period while HMRC expects a shorter Corporation Tax return from the trading start date. That works for a first year running from incorporation and for a later year in which the company was dormant at the start. Check your HMRC business tax account and CT603 notice before filing because HMRC may ask for a dormant-period return as well. Where HMRC expects the shorter period, we attach the full accounts and select CT600 box 85.
Pricing & payment
How much does SimpleCompanyTax cost?
Two simple prices, per company, per year: £10 for dormant companies (no trading activity in the period) and £25 for trading micro-entities (FRS 105). Both tiers include CT600 generation, iXBRL accounts, direct HMRC + Companies House submission, unlimited revisions, and downloadable documents. No hidden fees, no per-filing charges, no premium add-ons.
Why do you charge two different prices?
Dormant filings and trading micro-entity filings are genuinely different pieces of work: a dormant return has no P&L, no tax computation, no fiscal-year apportionment, and a smaller set of iXBRL tags. Pricing each tier accordingly is fairer (and cheaper for dormant filers) than averaging them into one number.
How can you charge only £10 for dormant filings?
Our focused scope lets us automate 99% of the computation and filing logic for dormant companies and micro-entities. We don't employ accountants to manually review every return, because the software handles validation and compliance checking automatically. By serving two well-defined markets, we build deep automation and pass the savings on.
What if my company was dormant last year and is trading this year?
No problem. You pick the plan that matches this filing year at checkout. Next year you pick again. We don't lock you into a tier.
What payment methods are accepted?
We accept all major credit and debit cards (Visa, Mastercard, Amex) via Stripe. All payments are processed in GBP. We never see or store your card details, because Stripe handles all payment security.
Can I get a refund?
If you're not satisfied with the service, contact support and we'll work with you to resolve the issue.
What happens when I use all my Practice slots?
You can add another Practice plan at any time from your Team page, and your total slots increase straight away. Each plan has its own renewal date and its own slots, so they do not need to line up. Cancelling a plan stops it renewing, and you keep using it until the end of the year you have paid for.
Eligibility & scope
What types of companies does SimpleCompanyTax support?
We support UK private limited companies that qualify as micro-entities, limited by shares or by guarantee, including trading, dormant, buy-to-let and property-only companies. We can also handle straightforward interest, dividends and chargeable gains. We do not support LLPs, PLCs, sole traders, partnerships or charitable companies, and we check the registered company type before you enter figures.
Can I file for a company limited by guarantee?
Yes. We file the CT600 and FRS 105 micro-entity accounts for a UK private company limited by guarantee, trading or dormant, to HMRC and Companies House together or to either one. We read the legal form from the Companies House record when you add the company, so there is nothing to select, and both Companies House forms are accepted, with or without Limited in the name. Being limited by guarantee does not by itself change the ordinary Corporation Tax calculation, which still depends on the company’s own activities, income and claims. The exception is a charitable company, which cannot use micro-entity accounts and needs the CT600E page.
Does a company limited by guarantee have share capital?
No. A company limited by guarantee has members who guarantee a small amount if the company is wound up, usually £1 each, and it has no shares. The wizard does not show the share capital rows for it. Capital and reserves are the retained earnings the company has built up, shown as members’ funds, and that total must equal net assets. The guarantee amount is not entered anywhere: it is not an asset, a liability or capital. If your records use an income and expenditure account, enter each amount by its nature: trading or business income as turnover, rent in the property fields, bank interest in interest received. The surplus or deficit is a cross-check, not a figure you type.
Can a dormant company limited by guarantee file accounts only?
Yes. Select Dormant on the eligibility step and, on the review page, choose Companies House only if HMRC has not asked for a Corporation Tax return for the period. A dormant guarantee company usually has a nil balance sheet with members’ funds of £0. Companies House accepts dormant accounts for companies limited by shares and by guarantee alike.
Is a charitable company limited by guarantee supported?
No. A charity is excluded from the micro-entity regime by the Companies Act, files accounts under the Charities SORP and claims its tax exemption on the CT600E supplementary page, none of which we produce. Companies limited by guarantee that are not charities are supported. If your company is a registered charity, answer Yes to the special-regime question on the eligibility step, keep the company in your account and contact support.
My flat management company is limited by guarantee. Can I file?
Yes. Residents’ management, right-to-manage and freehold companies can file whether they are limited by shares or by guarantee. Enter only the company’s own figures: ground rent it is entitled to, interest on its own money, its own bank balance and creditors. Service charges and reserve funds held on trust for the leaseholders under the lease are not the company’s income or assets, so keep them out. Many of these companies are dormant once trust money is excluded and file accounts only when HMRC has not asked for a return. We do not decide the lease position for you.
Do you support buy-to-let companies and property SPVs?
Yes, for supported UK micro-entities with UK rental property. Enter gross rental income and costs separately. A property-only company does not need to divide its running costs between businesses. Mortgage interest goes in Interest payable, and unused property losses go in Tax adjustments. You supply the applicable associated-company count.
Where are the audit exemption options?
You will not see separate audit-exemption questions. Supported micro-entity accounts are prepared as audit exempt under section 477, with the related section 476 and micro-entity statements. If the company needs an audit or members have requested one, SimpleCompanyTax is not suitable for that filing.
Do you support companies with associated companies?
Yes. Two companies are associated when one controls the other, or the same person or people control both, for example a director who owns a consultancy and a property company. HMRC divides the £50,000 and £250,000 Corporation Tax limits by the number of associated companies plus one. In the Tax adjustments section you enter the number of other companies associated with yours at any point in the accounting period (box 326, which is 0 for most companies), and we apply the divided limits and the marginal relief. We do not ask about it anywhere else and we do not decide for you whether companies are associated. Companies that carried on no trade or business in the period and passive holding companies do not count.
What is an associated company for Corporation Tax?
A company is associated with yours when one controls the other, or when the same person or group of people control both (Corporation Tax Act 2010, sections 18E to 18J). Control usually means more than half the shares, voting rights, income or assets. It counts if it was associated at any time in the accounting period, even for a day. Companies owned by a relative count only where the two businesses are substantially interdependent. Dormant companies with no trade or business and passive holding companies do not count.
How do associated companies affect Corporation Tax?
They divide the limits that decide your rate. The £50,000 small profits limit and the £250,000 upper limit are each divided by the number of associated companies plus one, so a company with one associate is tested against £25,000 and £125,000. That can move a company from the 19% small profits rate into marginal relief, or from marginal relief to the 25% main rate. Both limits are divided by the same number, so marginal relief always exists between them. We show the limits we applied on your review page.
Should I use box 326 or boxes 327 and 328?
Box 326 is the number of associated companies for the whole accounting period and is the box almost everyone uses. Boxes 327 and 328 replace it when the period straddles 1 April and either the number changed between the two financial years or the Corporation Tax limits changed between them (as they did on 1 April 2023). Box 327 is the number for the part before 1 April and box 328 for the part from 1 April. Across 1 April 2023 each part is restricted by its own number. For a later 1 April HMRC's calculation applies the higher of the two to the whole period, and we calculate the same way. HMRC accepts box 326 or boxes 327 and 328 together, never all three, so we only offer 327 and 328 when your period straddles 1 April. Leave box 326 at 0 to use them. Once one of 327 or 328 has a figure the other shows a dimmed 0 and files as 0 unless you change it.
What is a large or very large company for quarterly instalments (boxes 630 and 631)?
HMRC treats a company as large when its profits for the period, including dividends received, are more than £1.5 million divided by the number of associated companies plus one, and very large above £20 million on the same basis (for accounting periods beginning on or after 1 April 2019). Large and very large companies pay Corporation Tax in quarterly instalments and tick box 630 or box 631. There are exceptions, for example a first year as large with profits under £10 million, or a tax bill under £10,000. You tick the box yourself in Tax adjustments. We file what you tick.
Does SimpleCompanyTax calculate quarterly instalment payments?
No. We file box 630 or 631 if you tick it, and the previous-period count HMRC asks for from an instalment payer, but we never calculate the instalments, their dates, interest or penalties, and we do not work out whether your company is large. HMRC explains the rules in its guidance on paying Corporation Tax in instalments.
Can I file a return for a period before April 2023 that needs box 625?
Yes. For a return ending on or before 31 March 2023 there are no associated-company boxes (the rate was flat and HMRC does not allow boxes 326 to 328 on those returns). If the company was a quarterly instalment payer and you tick box 630 or 631, we offer box 625, the number of related 51% group companies at the end of the previous period including your own company, and file it as you enter it. Leave it blank if there were none. A period that starts before 1 April 2023 and ends after it files that count in box 326 instead.
Can I claim group relief?
No. Group relief (CT600C), group accounts and consolidation into a parent are outside what we file, and you confirm that when you add a company. Associated companies on their own are fine: you enter the number and we divide the limits. If your company surrenders or claims losses within a group, an accountant is the right route.
What companies are NOT supported?
Currently we don't support: R&D tax credit claims, group relief (CT600C), companies that prepare group accounts or are consolidated into another company's accounts, PLCs, LLPs, and companies with overseas permanent establishments. Companies with associated companies are supported: you enter how many and we divide the marginal relief limits. Short accounting periods are supported, including one-day stub returns, and we reduce the AIA and marginal relief limits for the shorter period automatically.
Can I file for an LLP (limited liability partnership)?
No. An LLP does not pay Corporation Tax or file a CT600, so SimpleCompanyTax cannot file for it. An LLP is taxed through its members personally and files an SA800 partnership return to HMRC plus LLP accounts to Companies House instead. You can tell an LLP by its company number, which starts with OC, SO or NC. If you add an LLP, we detect this at Companies House and let you know before you enter anything.
Which accounting periods can I file, and how far back can I go?
We support accounting periods starting on or after 1 April 2015, so you can file the current year as well as overdue returns for earlier years. If your accounting period starts before 1 April 2015, SimpleCompanyTax cannot file it. Please note that HMRC's own filing deadlines and late-filing penalties still apply to overdue returns, and HMRC may not accept a very old period online, so check your filing obligations before you start.
Is SimpleCompanyTax recognised by HMRC?
Yes. SimpleCompanyTax submits CT600 returns directly to HMRC via the Government Gateway Transaction Engine and files accounts with Companies House via the CH API. Production filings are accepted today.
My company name is longer than 56 characters. Can I still file?
Yes. HMRC allows 56 characters for the company name on a CT600, while Companies House registers names of up to 160. If your registered name is longer, we shorten it for the CT600 only, abbreviating common words first (Services becomes Svcs) and always keeping the Ltd or Plc ending. The wizard shows you the exact name HMRC will receive. Your accounts, tax computation and Companies House filing keep the full registered name, and HMRC matches the return on your UTR.
Can I use a loss from a previous year to reduce my Corporation Tax?
Yes. Enter an unused earlier trading loss in Trading losses brought forward under Tax adjustments. We set it against this year's trading profit and carry any remainder forward again. This relief does not reduce other income such as bank interest, and a claim to carry a new loss back to an earlier year uses a separate process. A company with no trade cannot use a trading loss and does not see this box. Check your last tax computation for what an earlier unused loss is: an unused UK property business loss goes in Property losses brought forward, where it reduces total profits, and an unused non-trading loan relationship deficit goes in its own brought-forward field. A loss from a trade the company has stopped stays a trading loss and cannot be set against rent.
What happens to a loss my company makes this year?
You don't need to do anything special. If your company makes a trading loss this year, SimpleCompanyTax reports it on your CT600 and it's carried forward automatically, ready to set against your profits in a future year. There's no Corporation Tax to pay on a loss-making year.
Where do I find my losses carried forward for next year’s return?
Open the tax computation PDF and use the section called "Losses carried forward to the next period". It lists the remaining trading, UK property business and capital losses. Do not use CT600 boxes 780, 805 or 825 because those report amounts arising in the current period, not the running balance available next year.
Some of my property losses are from before April 2020. Does that matter?
Not for a UK-resident company filing with us. Enter the full unused UK property loss in Property losses brought forward. The April 2020 restriction applies to certain non-UK-resident company landlords that moved from Income Tax to Corporation Tax, and those companies are outside our current scope.
My company made a loss but paid tax last year. Can I claim a refund by carrying the loss back?
Possibly, if an eligible current trading loss can be set against profit on which the company paid Corporation Tax in an earlier period. SimpleCompanyTax does not submit the carry-back claim, so make it separately with HMRC. You can enter the expected repayment in Tax adjustments so the accounts show Corporation Tax recoverable, but only enter an amount you reasonably expect to recover.
My company trades and also lets property. Why is my capital allowances claim blocked?
We currently file every allowance and balancing charge entered by a mixed company against its trade. We therefore ask you to confirm the whole claim belongs to the trade. If any part belongs to the property business, we cannot safely split it from one total, so an accountant should file that return.
My AIA claim is over the limit. Why do you refuse it rather than cap it?
The excess is not AIA. It normally enters a pool for a writing down allowance, which needs figures we do not hold. Automatically capping the entry could lose the remainder or file a claim you did not make. Correct a typo, or use an accountant if the genuine claim exceeds the date-adjusted AIA limit.
Can my buy-to-let company claim capital allowances on a new boiler or appliances?
Usually not for equipment used inside a home the company lets, including a boiler or appliance in a flat and shared HMO areas. Equipment serving only the common parts of a block, or used in commercial property, may qualify. A system serving both common parts and individual homes needs the cost split, so work out the qualifying part or ask an accountant, then enter that figure. We file the figures you supply and do not confirm eligibility.
The filing process
How long does the filing process take?
Most micro-entity directors complete everything in 15–30 minutes. Dormant companies are faster, often under 10 minutes.
Can I save my progress?
Yes. Your data is saved automatically as you go. You can close the browser and return at any time.
Can I submit a Company Tax Return using estimated figures, and when should I tick CT600 box 55?
HMRC allows estimated figures in some circumstances when final figures are not available despite the company’s best efforts. Use a reasonable best-estimate number, never placeholder wording instead of a figure. Select "This Corporation Tax return contains estimated figures" in the final standalone block on Financial data, after the Employees section. SimpleCompanyTax will mark box 55 on the return sent to HMRC. The selection does not change the figures or tax calculation.
What if I make a mistake?
Before filing, edit the figures and regenerate the watermarked draft as many times as you need. Nothing is sent to HMRC or Companies House until you complete the final filing step. If an accepted return is already on file, use the amendment process instead.
My filing was stopped before it was sent. What does that mean?
We found a problem that would have caused HMRC to reject the return, so nothing was sent. Correct the named figure in the wizard and file again. There is nothing to withdraw and no extra charge to resubmit. If you believe the figure is right, contact support with the filing reference.
Why is my CT600 or Companies House filing pending?
Pending means the regulator is still processing the filing, not that it has been rejected. HMRC and Companies House decide separately, so one side can be accepted while the other remains pending. Keep the filing reference and wait for the final status rather than submitting the same documents again.
Why is my taxable profit different from the profit in my accounts?
Accounting profit follows the accounts rules. Taxable profit starts from that result and applies Corporation Tax adjustments, such as adding back disallowable expenses and depreciation, then deducting qualifying capital allowances or reliefs. A difference is normal when the adjustments are correct.
Other software asked me to itemise salaries, audit fees and office costs. Why does this not?
Because we prepare the shorter FRS 105 micro-entity format, which reports expenses under a small set of statutory headings rather than a long itemised list. Salaries and other payroll costs are the exception: company law shows them as their own Staff costs line, which is why we ask for them separately. Professional fees, rent, insurance and office costs need no lines of their own and go in Other charges. The CT600 also reports turnover and trading profit rather than separate office, salary or accountancy-fee boxes. Enter depreciation in its own field so we add it back for tax, and keep the underlying records in case HMRC asks for them.
Where do I enter a bad debt or an unpaid invoice I have written off?
If your completed accounts include a bad-debt or trade-debtor impairment expense, enter that expense in Other charges. Our form uses the statutory micro-entity headings, so there is no separate Bad debts line. Include your current and previous period Debtors balances in the Current Assets totals exactly as shown in those accounts. Do not use the Depreciation and amounts written off assets field, which covers fixed assets and is added back for tax. If you have not yet worked out the accounting or tax treatment of the debt, an accountant can confirm it.
Where do I enter income that has no obvious box, like a one-off fee?
Use the Income not falling under any other heading row in the profit and loss step. It is for taxable receipts that fit no other row, such as a one-off referral or introduction fee earned outside your normal business, another casual one-off receipt, or a fixed cash bonus from your business bank. Enter the amount and we file it in CT600 box 205, within Other income in your accounts. We trust your classification, so use another category when one fits. Income your company earns as part of its normal business is turnover, not other income.
Is cashback or a bank switching bonus taxable for a limited company?
Yes. Cashback and rewards a company receives on its business banking are taxable, even though similar rewards on a personal account usually are not, because companies are taxed on their profits under different rules. How you record it depends on what it was: cashback earned on business spending is a rebate, so reduce the expense it relates to, while a standalone reward such as a switching or joining bonus is income and goes in box 205. Anything worked out from your balance or an interest rate is interest and belongs in Interest receivable. Cashback earned on a director personal card belongs to the director and is not company income at all.
Where do I enter cashback or a bank reward? I cannot see an other income box.
Cashback earned on business spending is normally deducted from the expense it relates to, so reduce Other charges or Cost of raw materials by the amount, and there is nothing else to enter. A fixed promotional cash reward paid separately by your business bank, and not calculated as interest, is taxable and goes in the Income not falling under any other heading row, which files in CT600 box 205 and appears within Other income in your accounts. Anything worked out from a balance or interest rate is interest and belongs in Interest receivable instead.
Where do I enter charitable donations?
Leave the payment in your expense figures and enter the same total in Charitable donations under Tax adjustments. We add it back to trading profit and claim the qualifying amount in CT600 box 305, capped at the company's available profits. If your company only lets property, enter the amount on the Charitable donations row in the Profit and loss expenses block, once, and leave it blank if the company gave nothing. It becomes the Other charges line in your accounts and the relief is claimed the same way. The field covers cash gifts to a UK registered charity or registered CASC where the company and connected people received nothing in return. If your accounting period is longer than 12 months, it files as two returns and you tell us which return the donation belongs to, based on the date you paid it.
Charitable donations and Corporation Tax relief, explained →
Where do I enter entertaining, fines and other disallowable expenses?
Enter the cost in both places. Leave it in the relevant expense total so the accounts show the real cost, then enter the same amount in Disallowable expenses under Tax adjustments. We add it back when calculating taxable profit. A £1,000 fine normally appears in Other charges and as £1,000 of disallowable expenses.
Can I claim costs from before my company started trading?
Yes, if the company incurred them and they qualify. Revenue costs from the seven years before trading began, incurred wholly for the trade, are treated as spent on the first day of trading and reduce the taxable profit or increase the trading loss of the period trading started. If the costs were expensed in an earlier year's accounts, before the trade existed, enter the qualifying total in the Qualifying pre-trading expenditure field under Tax adjustments and we deduct it in the tax computation without changing your accounts. Costs already inside this year's expense figures are being deducted through those figures, so do not enter them again. Costs from before the company was incorporated are not automatically company expenditure, and company formation fees are capital.
How do I record or release a provision for liabilities?
Provisions are entered as closing balances, not journals. On the balance sheet step, use the link that adds the optional lines to reveal Provisions for liabilities, then enter this year’s closing provision and last year’s in the prior-year column. To release a brought-forward provision, enter last year’s figure and the reduced balance, or zero, for this year, and include the effect of the release in your expense figures. If the provision was previously disallowed for tax, contact us with the details before filing and we will confirm whether it fits the supported route while we review support for that case.
What do I enter for capital allowances?
Enter each claim separately under Tax adjustments. Use AIA for qualifying equipment bought in the period, then record any special rate part in the field beneath it. Fixtures like wiring, heating and air conditioning DO qualify for AIA when bought this period, so they go in the AIA figure and that field only records how much of it they are. Use the separate fields for writing down allowances, a qualifying new electric car, structures and buildings allowance or balancing charges. Cars never qualify for AIA, and full expensing or other unsupported first year allowances need an accountant.
How do capital allowances work when my first accounting period is longer than 12 months?
We show both Corporation Tax return date ranges and ask you to assign each capital allowance, pool addition and balancing charge between them. The suggested day-count split is only a starting point. Change it to match the actual purchase or sale dates, then confirm that both amounts add back to the total.
Where do I enter a balancing charge for an asset I sold?
Enter any accounting profit on the sale in Profit on disposal of fixed assets, then enter the computed balancing charge in the main or special rate pool field under Tax adjustments. Work the charge from the disposal value and pool balance, not directly from the sale price. Any taxable amount above original cost is a chargeable gain rather than a balancing charge.
My company gets rental income from property. How do I enter it?
Enter rent for the accounting period before expenses in Property rental income. Enter rental costs in Property income and expenses and mortgage interest separately in Interest payable. If the company also trades, enter trading costs in the separate trading section. Older net-only drafts keep their existing meaning unless you choose to enter gross rent and separate expenses.
How do I split expenses when my company trades and rents out property?
Enter trading costs in Trading income and expenses and letting costs in Property income and expenses. For shared costs, enter your allocated amount in each section without duplication. Enter property tax adjustments under Property tax treatment. We combine the business figures for annual accounts and use your classification without asking for evidence.
Can I use my own calculated property profit or loss?
Yes. Enter your property tax base before capital allowances, balancing charges and losses, including your property tax adjustments. Blank uses our calculation, 0 uses a zero base and a negative figure represents a loss. The override changes property tax, not gross accounts or the trading remainder. Mixed companies still need cost allocations.
My company sold a property or investment at a profit. Can I file the gain?
Yes, for a straightforward chargeable gain that you have calculated. Enter the gross gain and current or brought-forward capital losses under Tax adjustments, and enter the accounting profit on disposal separately for the accounts. Connected-party sales, potentially exempt share disposals, ATED-related gains and non-resident cases need an accountant.
Our company owns property and UK listed shares. Can you file our return?
Usually, if the company qualifies as a micro-entity. Associated companies are fine: you enter how many. Enter rent, dividends, investments and any chargeable gain in their separate fields. FRS 105 records property and shares at cost rather than market value, and you must calculate any share disposal gain using the applicable pooling rules.
Can we show our investment property or shares at market value?
No. Our FRS 105 accounts carry investment property at cost less depreciation and impairment, and investments at cost less impairment. Enter what the company paid, not today's market value. If you need fair-value or revalued accounts, you need FRS 102 Section 1A accounts and an accountant.
Where do I enter share premium? The help text says not to add it to share capital.
Enter share premium and other non-share-capital reserves in Retained earnings. Keep Share capital to the nominal value of issued shares so it matches the Companies House register. FRS 105 filed accounts show one combined Capital and reserves total, but share premium is still not a distributable profit.
My shares were issued but never paid for. What do I put for share capital?
Enter the nominal value in Share capital and the unpaid amount in Called up share capital not paid. For one unpaid £1 subscriber share, enter £1 in each field. Do not reduce Share capital to zero or put the unpaid amount in Debtors because an issued share remains on the register and the unpaid amount has its own statutory balance-sheet line.
Where do company running costs go if the company has no trade?
Match the cost to the activity it supports. Deduct property letting costs inside the net property figure. Investment-management costs use a separate tax treatment and are not a second claim for costs already deducted from rent. Contact us before filing if a non-trading company has genuine management expenses because we need to check the treatment.
The company received dividends from another company. Are they taxed?
Most dividends received from another company are exempt from Corporation Tax, but they can increase augmented profits and change whether the company pays 19%, 25% or marginal relief. Enter them in Dividends received and we report box 620 and apply the rate rules. We do not support group companies.
What formats do you deliver?
Your filing record contains the submitted CT600 XML, the full iXBRL accounts for HMRC, the iXBRL accounts filed to Companies House, the iXBRL tax computation and regulator receipts. By default the Companies House copy is filleted, meaning the balance sheet, statements and notes with the profit and loss account withheld. If you chose to publish the profit and loss account, the Companies House copy is the full accounts, identical to the HMRC copy. You also get readable PDFs of the official CT600 form, both accounts versions and the tax computations, with page numbers. The exact set depends on whether you filed to HMRC, Companies House or both.
What date should I enter as the accounts approval date?
Enter the date the directors approved the finished annual accounts. We default it to today, but you can change it. It cannot be before the accounting period ended or in the future. The date appears on draft and final accounts. It can differ from CT600 box 980 because that box records the return declaration date, which is the preview date on a draft and the HMRC filing date on the final CT600 PDF.
Which approval dates do I enter for revised accounts?
Enter the date the directors approved the revised accounts in the amendment panel. Enter the original accounts approval date in the preview or final filing details, using the date printed on the original accounts, not the date they were filed. If you change a date after downloading a draft, generate a fresh preview and check both dates before filing.
My first accounting period is longer than 12 months. What do I do?
Enter the full accounts period once. If the company was within the charge to Corporation Tax for the whole of it, we create the two Corporation Tax returns HMRC requires and one set of Companies House accounts for the full period. Income and running costs are shared by day count. If you have capital allowances or a balancing charge, confirm which return contains the purchase or sale instead of relying on the suggested split. If the company was dormant at first and started trading later, check your CT603 notice: HMRC expects one return from the trading start only where their records show that later date.
My company was dormant and started trading later. Which periods do I enter?
Enter your full annual accounts period, from incorporation in a first year or from your year start in a later year, up to the Companies House year end. If your HMRC business tax account and CT603 notice show one Corporation Tax return from the date trading started to that same year end, select the separate HMRC period option and enter the later start date. We attach the full accounts and select CT600 box 85. A later year keeps its comparative figures as normal. If HMRC also asks for a dormant-period return, contact us before filing because that is not this one-return route.
I changed my company year end. What do I do about the CT600?
Change the accounting reference date with Companies House first, then check the Corporation Tax period dates HMRC has set. If the full accounts period is over 12 months and up to 18 months, enter it once. SimpleCompanyTax prepares one set of annual accounts and the two CT600 returns HMRC requires. Use confirmed dates, not guessed dates.
Why is an expense split between my two Corporation Tax returns?
A long first year needs two Corporation Tax returns, so we share whole-period income and running costs between them by day count. Nothing is counted twice, and a loss from the first return carries into the second. If transaction-date allocation is important, file the Companies House accounts and the two HMRC returns as separate filings.
Do you file to both HMRC and Companies House?
Yes, and you choose what to file at the very first question. "What are you filing?" offers the CT600 to HMRC, the annual accounts to Companies House, or both, and both is the default. Pick one and everything after it adapts. If you change your mind later you do not have to start again, because the final screen lets you add or remove either destination before you submit.
I’ve already filed my accounts to Companies House. Can I file just the CT600 to HMRC?
Yes. At "What are you filing?", choose HMRC CT600. We prepare and send only the Corporation Tax return, and the final step asks only for HMRC credentials. This works whether the accounts were filed through us or elsewhere. You can add Companies House again on the final screen.
Can I file only my accounts to Companies House (not the CT600)?
Yes, and it is one click. At the first question, "What are you filing?", choose Companies House. Only the annual accounts are prepared and sent, and the single credential you need at the end is your 6-character authentication code. Most companies still owe HMRC a CT600 as well, so pick this when your CT600 is already filed or is not yet due. You can add HMRC back on the final screen if that changes.
I don't have a Government Gateway account set up for Corporation Tax. How do I create one?
Create Government Gateway sign-in details for the business, then add Corporation Tax for the company using its UTR and company number or registered postcode. HMRC normally posts an activation code to the registered office, so start well before the filing deadline. Use the account enrolled for the company you are filing, not a personal tax account.
HMRC says my sign-in details are wrong but I am sure they are correct. What now?
HMRC uses the same Authentication Failure message for several problems. Sign in with the same Government Gateway ID and check that Corporation Tax is listed, the enrolment is active and the 10-digit UTR matches the company you are filing. A correct password on the wrong or unactivated account will still fail. Nothing was filed, so you can correct the details and try again.
My company's UTR does not appear in my HMRC online account. What do I do?
If Corporation Tax is missing, add the service and activate it with the code HMRC sends. If another company's UTR appears, use the Government Gateway account enrolled for the company you are filing. If HMRC holds the wrong link, contact the HMRC Online Services Helpdesk. The Corporation Tax UTR is a 10-digit company reference, not your personal UTR or company registration number.
Where can I find my company UTR for Corporation Tax?
Your company UTR is the 10-digit Corporation Tax reference on HMRC letters, previous Company Tax Returns and your Business Tax Account. It is not your personal UTR or Companies House company number. If you cannot find it, request a Corporation Tax UTR online and HMRC will send it to the business address registered at Companies House.
What is a Companies House authentication code? Is it the same as my personal code?
The company authentication code is a 6-character code that authorises online filings for one company. It is not the Companies House personal code used for identity verification. Request it through Companies House WebFiling if you do not have it. It is posted to the registered office, or an eligible officer can ask for it at their home address.
What credentials do I need to submit, and where can I find them?
You will be asked for the relevant details at the final step, immediately before filing.
For Companies House (statutory accounts filing):
You will need your company's 6-character Companies House authentication code. This code is sent by post to your registered office address. If you do not have it, you can sign in to Companies House WebFiling and select “Request an authentication code”. It can take up to ten working days to arrive, so request it well before the filing deadline.
For HMRC (Corporation Tax return filing):
You will need:
- Your company's 10-digit Corporation Tax Unique Taxpayer Reference (UTR)
- The Government Gateway user ID and password for an account that is enrolled for Corporation Tax for the company
Your Corporation Tax UTR can be found on HMRC Corporation Tax correspondence or within your Business Tax Account. If you have forgotten your Government Gateway user ID, you can recover it through the HMRC online services portal.
For security, your credentials are used only for this submission and are never stored. Your Government Gateway details and your Companies House authentication code are both transmitted for the filing and then discarded. You re-enter them next time you file.
You also confirm the director approving the accounts and the accounts approval date. Those details appear in the accounts and are saved with the filing.
Will my turnover and profit be public when I file my accounts?
For a micro-entity filing now, Companies House receives the smaller public accounts version, which does not include the profit and loss account. HMRC receives the full accounts and tax computation with the Corporation Tax return. Companies House has announced changes from April 2028, when micro-entities will send a profit and loss account but can opt out of publishing it on the public register.
Why can I not put my car in the Annual Investment Allowance field?
Cars are excluded from AIA. Use the main or special rate writing down allowance according to the car's CO2 emissions, or the separate 100% field for a qualifying new zero-emission car. Vans and other commercial vehicles are not cars for this rule and can qualify for AIA.
Do the "Added to the pool this period" fields change my tax?
No. They are cost disclosure only. HMRC asks the return to report what the company spent on assets that went into a pool this period, in boxes 770 and 775, alongside any allowance claimed. Your tax comes from the allowance fields, and you report an addition whether or not you claim a writing down allowance on it this year.
What does "Of which is special rate items" under the AIA field mean?
It is the part of the AIA total spent on special rate items, such as integral features, solar panels, thermal insulation and long-life assets. It is included in the AIA figure above, not added to it. Cars never belong here because they cannot use AIA. We ask only because HMRC reports each pool's share separately.
Why is my car's cost not in box 770?
Because HMRC excludes special rate cars from box 770 and has them reported in box 775 instead. Box 770 covers the rest of your special rate spending, such as integral features, solar panels and long-life assets. When you tell us the cars part of your special rate additions, we move that part to box 775 for you. It does not change your tax, only where the cost is disclosed.
Do I still work out the structures and buildings allowance myself?
No. Add one claim line for each amount on the allowance statement and enter its qualifying expenditure and dates. We calculate the ordinary 2% or 3% annual allowance, including a blended rate across April 2020 and separate calculations for two returns in a long first period. The tax computation shows the working.
Can SimpleCompanyTax file the enhanced 10% structures and buildings allowance?
No. Enhanced 10% SBA for qualifying freeport or investment-zone expenditure needs CT600M, which we do not produce. We support ordinary 2% or 3% SBA. If the allowance statement identifies a special tax site or enhanced claim, do not reclassify it as ordinary. Ask an accountant to file it.
Why do you ask for the building's cost every year when box 771 is only for a first claim?
The yearly allowance is calculated from the qualifying expenditure on the allowance statement, so we need that cost every year. We only put it in box 771 when you identify the return as the first claim. In a long first period it is reported once, on the first return in which that claim accrues.
Is the main pool writing down allowance still 18%?
It depends on your dates. The rate is 18% a year for accounting periods ending before 1 April 2026 and 14% a year for periods starting on or after that date. A period that straddles 1 April 2026 uses a hybrid rate between the two, and GOV.UK publishes a guide for working out the exact blended figure. The special rate pool is unchanged at 6% a year, and it was 8% a year before April 2019.
After you file & paying HMRC
I made a mistake on a return I already filed. Can I correct it?
Yes. Open the accepted filing and choose "Amend this filing". Change the pre-filled figures, explain the correction and select whether HMRC, Companies House or both need the revision. HMRC amendments normally close 24 months after the accounting period ended. A rejected filing has not been accepted, so correct it and submit again instead.
When will my Corporation Tax show in my HMRC account after I file?
Usually within a few working days after HMRC accepts the CT600, although HMRC does not guarantee a timescale. Your SimpleCompanyTax acceptance record already shows the tax figure, so you can pay with the correct accounting-period reference without waiting for the online balance to update.
Can I pay HMRC before the amount shows in my account?
Yes, and you often should. Corporation Tax is self-assessed, so you can pay as soon as you know the figure (your filing receipt shows it) without waiting for the portal to update. As long as you use the correct 17-character payment reference for the accounting period, HMRC matches your payment to the right period. This matters because the deadline to pay is earlier than the deadline to file.
Do I need to choose the accounting period when I pay?
Effectively yes, and you do it through the payment reference. There isn't a separate "which year?" step. The 17-character reference is how HMRC knows which accounting period your money belongs to. Use the reference for the period you're paying and the payment lands against that period. Paying the right amount with the wrong period's reference is the most common mistake.
Is my Corporation Tax payment reference the same every year?
No. The 17-character payment reference is your fixed 10-digit UTR plus a suffix that identifies the specific accounting period (for example 1234567890A00108A). Your UTR stays the same, but the full reference is different for every accounting period, so don't reuse last year's. You'll find the correct one on HMRC's payment reminder/payslip or in your HMRC online account when you select the period to pay.
How do most people pay their Corporation Tax, and by when?
Most companies file, then pay HMRC directly by bank transfer using that period's 17-character reference. Corporation Tax is usually due 9 months and 1 day after the accounting period ends, while the CT600 is due after 12 months. SimpleCompanyTax files the return but does not collect the tax.
How do I tell HMRC this is my final CT600 because the company has stopped trading?
There is no final-return box. File the last CT600 to the date trading stopped, then separately tell HMRC the company is dormant. If you are closing the company, follow the Companies House strike-off process as well. Filing the CT600 alone does not stop HMRC expecting later returns.
HMRC sent my company a tax determination. What should I do?
A determination is HMRC's estimated Corporation Tax bill because a required CT600 was not filed. It is not the company's final tax calculation. Identify the period, file the accurate return and pay the tax due promptly. You may be able to appeal a late-filing penalty, but HMRC says to file the return first.
Data & security
Where is my data stored?
On managed UK cloud infrastructure. Data is encrypted at rest (AES-256) and in transit (TLS 1.2+).
Can I delete my data?
You can request deletion of your account and personal data. We may still need to retain filing records for the period required by tax, accounting and legal obligations, which is generally at least 6 years. Our Privacy Policy explains the retention rules and your rights.
Do you sell my data?
No. Never. Our Privacy Policy sets out exactly how we process and share data.
Still have a question?
Support responds within one working day, sooner if your filing deadline is close.