How to file company tax in the UK
The end-to-end process for directors. Read →
GUIDES
Guides for UK company directors.
Plain-English explanations of the terms, deadlines, and decisions that come up when you run a UK limited company. No accountancy jargon. No upsells.
REFERENCE
Key reference guides.
Long-form references on the core mechanics of UK company tax filing.
What is a CT600?
The electronic corporation tax return, explained. Read →
What is a micro-entity?
Thresholds, filing rules, and when they change. Read →
Dormant company tax return
HMRC dormancy and the CT600 side. Read →
Can I file company tax myself?
Realistic guide to self-filing. Read →
File dormant accounts online
Companies House dormant accounts in one flow. Read →
Can I file only the second CT600 if the first return is already filed?
Filing the outstanding short-period CT600 after the first return, including accounts attachments, losses and using different software. Read →
CT600 box 595 explained: Corporation Tax already paid
A practical explanation of box 595, payment records, refunds and the difference between tax liability and tax outstanding. Read →
How to file a CT600 if Corporation Tax is already paid
A step-by-step filing guide for companies that paid their Corporation Tax before submitting the return. Read →
How to file a CT600 with Corporation Tax partly paid
Worked examples for part-paid Corporation Tax, a fully paid bill and an overpayment, with the remaining balance explained. Read →
CT600 rounding: should you round company figures up or down?
Worked rounding examples, whole-pound turnover, tax calculated in pence and what HMRC and FRS 105 actually say. Read →
Can CT600 dates be different from Companies House accounts?
Why CT600 and Companies House accounts dates can differ, with common examples, date checks and filing deadlines. Read →
Wrong HMRC Corporation Tax period dates: how to correct them
How to check incorrect HMRC dates, what information to provide and when a Companies House year-end change is a separate step. Read →
How to set different CT600 dates from Companies House
Step-by-step instructions for entering different CT600 and Companies House accounts dates, checking figures and reviewing the filing. Read →
Micro-entity size limits, short accounts and the two-year rule
Examples for six-month and 18-month accounts, first-year qualification and changing company size. Read →
Understanding iXBRL accounts and tax computations
What the tags mean, why bracketed deductions can be positive facts, and how your classifications reach the filing. Read →
Brought-forward capital losses for limited companies
Capital losses reduce chargeable gains, not trading profits. Learn when the carried-forward loss restriction matters. Read →
How to enter brought-forward capital losses in your Corporation Tax return
Enter gross gains, current losses and the unused opening pool, then review the deduction and closing balance. Read →
How to enter a director's loan waiver
Record the released amount, effective date and tax treatment, then enter the balance still owed in one or both creditor fields. Read →
What is a non-trading loan relationship deficit?
A plain-English explanation of non-trading loan deficits, with a property-company example and official HMRC guidance. Read →
Where to enter a brought-forward non-trading loan relationship deficit
Enter your unused deficit, choose each return’s claim and understand a £0 maximum or a balance carried forward without a claim. Read →
Accounting profit vs taxable profit: why the figures differ
Your accounts profit is the starting point. Taxable profit applies the Corporation Tax adjustments. Read →
How to amend a CT600
Correct a filed return: HMRC amendments and Companies House revised accounts, step by step. Read →
After filing: CT600 and Companies House status explained
Your status shows whether the regulator is still processing, accepted the filing or needs a correction. Read →
Audit exemption for micro-entity accounts
Why audit-exemption settings are applied automatically to supported accounts. Read →
Changing your company year end and Corporation Tax period
Change the accounting reference date with Companies House first, then make sure HMRC has the right Corporation Tax period. Read →
Companies House authentication code: where to find or request it
The 6-character code needed for Companies House filing, how to request it and why it is not your personal code. Read →
Why we ask for fewer expense figures than other software
The statutory headings, including the separate Staff costs line. It is the micro-entity format, not missing information. Read →
CT600 box 55: using estimated figures in a Company Tax Return
A practical guide to CT600 box 55, reasonable best estimates and filing a Corporation Tax return before every figure is final. Read →
Bad debts: where to enter an unrecoverable customer invoice
A bad-debt expense from your completed accounts goes in Other charges. There is no separate Bad debts line in the micro-entity format. Read →
Capital allowances and AIA: what SimpleCompanyTax supports
Where to enter AIA and other capital claims, including the two-return split for a long first period. Read →
Company cars and capital allowances: which field your car goes in
New EV, used EV, hybrid or petrol: the field each company car goes in, why cars never get AIA, and why a partial claim needs an accountant. Read →
CT600, annual accounts and confirmation statement: what is the difference?
They are three separate obligations. We file the CT600 and annual accounts, not confirmation statements. Read →
Where to find your company UTR for Corporation Tax
Find or request your company’s 10-digit UTR, then use it to set up Government Gateway and file the CT600. Read →
HMRC tax determination: what to do if you did not file a CT600
A determination is HMRC’s estimate when a CT600 is overdue. File the actual return and pay what is due promptly. Read →
Structures and buildings allowance: what to enter, year after year
Enter the allowance-statement cost and dates, and we calculate ordinary SBA for each Corporation Tax return. Read →
Capital allowances for landlords: what a property company can claim
The dwelling rule, HMO vs block of flats, and how we file the capital-allowance figures you supply. Read →
Balancing charges: selling an asset you claimed capital allowances on
Sold an asset you claimed AIA on? Where to enter the balancing charge and profit on disposal. Read →
Is business bank cashback taxable for a limited company?
Cashback, switching bonuses and account rewards: what is taxable for a company and where each one goes. Read →
Other income on your CT600: one-off receipts, box 205 and cashback
One-off fee, bank bonus or another receipt with no obvious row? Where other income goes, including box 205. Read →
Selling a property or investment: chargeable gains on your CT600
Calculate company disposal gains and supply the individual workings with CT600 boxes 210 to 220. Read →
We cannot work out the Corporation Tax for this return yet: what each message means
Blocked estimate? Every message in the panel, what it means, and exactly how to clear it. Read →
CT600 filing errors, explained
Understand common HMRC rejection codes, and the checks that stop a bad return before it is sent. Read →
Charitable donations: where to enter them and how the Corporation Tax relief works
Leave the donation in your expenses and enter it in the Charitable donations field. We add it back and claim the relief in CT600 box 305, capped at your profits. Read →
Disallowable expenses: entertaining, fines and your Corporation Tax
Entertaining and fines stay in your accounts but are added back for tax. Here is how to enter them, and why charitable donations are handled differently. Read →
Dividends in your accounts
Where dividends paid and received appear in your annual accounts. Read →
Associated companies and your Corporation Tax rate
Companies under common control divide the Corporation Tax limits between them. Enter how many in box 326 (or 327 and 328), tick 630 or 631 if the company pays by instalments, and we apply the divided limits. Read →
Dividends received and your Corporation Tax rate
Classify taxable and exempt dividends, understand mixed receipts and check the effect on your Corporation Tax rate. Read →
Companies that own property and shares: what we can file
Owns property and listed shares? How each part is taxed, and the FRS 105 rules that apply. Read →
Filing to HMRC, Companies House, or both
Pick your filing destinations at the first question, and change them later if you need to. Read →
Final CT600 when your company has stopped trading
File the last Corporation Tax return and stop HMRC expecting another one. Read →
Setting up a Government Gateway account to file Corporation Tax
Create a Government Gateway ID, add Corporation Tax, and link your company UTR before you file. Read →
HMRC rejected my sign-in details but they are correct
Sure your details are right but HMRC keeps refusing them? One error covers five different causes. How to tell which. Read →
LLPs: what you file instead of a CT600
Why an LLP files an SA800 rather than a CT600, and why we cannot file for LLPs. Read →
Claiming pre-trading expenses on your Corporation Tax return
Qualifying costs from before trading began are deducted in the period trading started, using the Qualifying pre-trading expenditure field. Read →
Dormant company started trading: accounts and CT600 dates
Your annual accounts cover the whole period while HMRC expects a shorter CT600 from the date trading started. Read →
Your first year: filing when your accounting period is over 12 months
Why a long first period usually needs two CT600s, and when it needs only one. Read →
How your figures are shared between two Corporation Tax returns
Why day count decides each return’s share, why the tax result is the same, and how to place amounts by transaction date instead. Read →
Loss carry-back claims and Corporation Tax refunds
Show an expected refund in your accounts and make the claim with HMRC. Read →
Paying your Corporation Tax after you file
When and how to pay HMRC using the correct accounting-period reference. Read →
Accounts approval date: what to enter and where it appears
Use the date the directors approved the accounts. See where it appears and why the CT600 date differs. Read →
PDF copies of your filing documents
View, print, and share PDF copies of everything that was filed, including next year’s carry-forward figures. Read →
Buy-to-let and property income on your CT600: rent, expenses and losses
Separate trading and rental income, property expenses, prior-year comparatives, manual property tax bases and worked examples. Read →
What company accounts are public at Companies House?
The public Companies House version is not the same as the full accounts and tax documents sent to HMRC. Read →
Which company types SimpleCompanyTax supports
We file for UK private limited companies, limited by shares or by guarantee, that are micro-entities. See what is in and out of scope. Read →
Companies limited by guarantee: filing the CT600 and accounts
We file the CT600 and micro-entity accounts for a company limited by guarantee, trading or dormant. The legal form is read from Companies House, there is no share capital to enter, and the balance sheet shows members’ funds. Charitable companies are the exception. Read →
Flat-management, RTM and freehold companies: accounts and the CT600
Enter only the company’s own figures. Service charges and reserve funds held on trust under the lease are not the company’s income or assets. Many management companies are dormant and can file accounts only. Read →
Where share premium and other reserves go in micro-entity accounts
No separate share premium line in FRS 105: where it goes, why that is compliant, and the dividend catch. Read →
Called up share capital not paid: shares issued but never paid for
Unpaid subscriber shares: enter the nominal value in Share capital and the unpaid amount in Called up share capital not paid. Read →
Provisions for liabilities: recording, increasing and releasing them
Provisions are entered as balances. To release one, fill the prior-year cell and the reduced current-year figure. Read →
Using trading losses to reduce your Corporation Tax
Use an earlier trading loss against this year’s trading profit. Read →
Know the rules. File with confidence.
From £10 per company, per year. CT600, iXBRL, and Companies House — one flow.