How to set different CT600 dates from Companies House

CT600 dates onlyAccounts keep their datesAny accounts period, first or laterWhere you see it: Company Profile & Period › under Filing purpose

Before entering figures, the filing setup questions can set the existing destination and CT600 route for an ordinary limited company. They keep the full accounts dates beside the CT600 dates. You can also continue with the controls below without opening the questions.

Is this the right option for you?

Common mistake: ticking it for a first period over 12 months

Aspen Example Ltd's first accounts run from 10 June 2024 to 30 June 2025. Its CT603 shows a Corporation Tax period of 10 June 2024 to 9 June 2025. That looks like a different period, but it is only the first of the two returns HMRC expects for a first accounts period longer than 12 months. For that shape the wizard shows a note under the box that starts Not needed for a first accounting period longer than 12 months.

Ticking the box and entering the first return's dates and figures files one return. The second return, for 10 June 2025 to 30 June 2025, is not filed, and the profit and loss in the attached accounts leaves out those 21 days. Leaving the box unticked files both returns from the full accounts figures.

A dormant start inside a long first period is different. If HMRC's dates start later because the company was dormant at first, ticking the box is right even though the note appears. Dormant company started trading

More help: Your first year: filing over 12 months · GOV.UK: Corporation Tax accounting periods

Why HMRC accepts accounts for a different period

A CT600 must be delivered with the company's full accounts. When the accounts cover different dates from the return, HMRC's CT600 guide says to enter X in box 85, which tells HMRC the accounts are for a different period. We tick box 85 for you and attach the same full accounts to each return. Your accounts are never cut down to the Corporation Tax dates.

One case is different. When a second return lies wholly after the accounts end, the accounts go with the first return, and box 90 on the second return gives HMRC the reason that the accounts were sent with the other return.

More help: HMRC Company Tax Return guide: boxes 80, 85 and 90 · HMRC CTM93180: accounts to deliver · Which accounts go with your first CT600

Worked example

Company

Juniper Example Ltd

Accounts period

1 January 2025 to 31 December 2025. A later year with comparatives

What happened

Dormant from 1 January 2025. Started trading on 1 April 2025

HMRC’s Corporation Tax period

1 April 2025 to 31 December 2025, on the CT603 notice. No CT600 filed yet

Figures from the full accounts

Turnover £64,000, staff costs £18,000, other charges £21,000

The company and all figures on this page are fictional.

Before you start

HMRC’s Corporation Tax dates

From your CT603 notice to deliver a Company Tax Return, or the Corporation Tax section of your HMRC business tax account. If you are unsure whether the dates should differ, read when CT600 and accounts dates can differ.

Your accounts dates and figures

The full approved accounts for the whole accounts period, as filed or to be filed at Companies House.

Activity before the Corporation Tax start

Whether the company had any income, gains or other activity before HMRC's start date. You confirm this in the wizard. HMRC: active and dormant for Corporation Tax

Company UTR and Government Gateway details

Where to find your UTR · Government Gateway for Corporation Tax

The company and all figures on this page are fictional.

If the first CT600 was already filed with the full accounts and only the second short period remains, use the second-return filing guide. Do not confirm no earlier taxable activity if the company was trading during the first period.

To file Companies House & HMRC CT600 together with different tax dates, choose Enter figures separately. Follow the separate figures guide for the financial entry steps. This guide describes Enter my figures once. For incorrect HMRC records, follow the date-correction checklist first.

Companies House is separate. Enter my figures once with different tax dates is available for supported HMRC CT600 filings, including a later year. It does not file your annual accounts at Companies House. Those accounts still need to be filed separately when required. The generated accounts are included in the HMRC filing package.

Step by step

1. Start a new filing

   Dashboard, company card

   Click New filing. If you see Resume filing, click the small arrow beside it and choose Start new filing →

   Confirm the company

   Tick the confirmation box, then click Continue with this company →

2. Company Profile & Period

   Accounting period

   1 January 2025 to 31 December 2025The full accounts period, with its statutory start and end. If it is not listed, choose Custom dates. Do not shorten the accounts dates to make the CT600 fit.

   Special tax regimes

   No

   What are you filing?

   HMRC CT600Or Companies House & HMRC CT600, which needs Enter figures separately further down.

   Filing purpose

   Standard return

   My HMRC Corporation Tax period is different from my statutory accounts period.

   Tick itThe Corporation Tax date fields and the confirmations open below it.

   Corporation Tax period start

   1 April 2025The start date HMRC shows. Usually the day trading began.

   Corporation Tax period end

   31 December 2025Filled in with the accounts end when you tick the box. Change it only if HMRC’s period ends on a different day.

   Check the preview

   We will prepare one Corporation Tax return: 1 April 2025 – 31 December 2025The note under it says the same full accounts go with every return.

   These dates match my CT603 notice to deliver a return, or my HMRC business tax account.

   Tick itCheck the dates against the CT603 or the business tax account first.

   Between the start of the accounts period and the Corporation Tax start date above, the company had no income, no chargeable gains and no other activity that brought it within the charge to Corporation Tax. Any costs in that gap are qualifying pre-trading expenditure or are included in the disallowable expenses figure.

   Tick it if it is trueShown with Enter my figures once when the Corporation Tax start is on or after the accounts start. Look at the months before 1 April 2025 before you tick it. Costs before the Corporation Tax start

   Trading status

   ActiveThe form starts on Dormant, so make sure you change it.

   How do you want to enter your figures?

   Enter my figures onceShown once Active is selected. Enter figures separately lets you enter the accounts figures and each CT600's figures apart.

   What the company does

   Trading

   Read the return-count preview and complete the confirmations shown before continuing. Then click Next →.

   More help: Date rules · GOV.UK: Corporation Tax accounting periods

3. Financial Data

   Enter the figures from the full approved accounts for 1 January 2025 to 31 December 2025, including costs from before 1 April 2025. Do not reduce them for the shorter dates.

   Previous year

   Last year’s figures, from your previous accountsRequired before you continue. Figures from Companies House fill in where available. Check them, and enter 0 where a line had no amount.

   Turnover

   64000Box 145

   Cost of raw materials and consumables

   0

   Staff costs

   18000

   Other charges

   21000

   Company tax type

   Standard companyCompany tax types and CT600 box 4

   Disallowable expenses

   Any cost in the accounts that is not deductible for Corporation TaxLeave Qualifying pre-trading expenditure empty for costs already in the expense lines.

   Balance sheet

   Your balance sheet at 31 December 2025Always at the accounts end, not the Corporation Tax end.

   Average number of employees

   Your average number, or 0

   Click Next →, then Review filing.

   More help: How your figures are treated

4. Review & file

   Check the Corporation tax due card. For Juniper Example Ltd it shows:

   Corporation tax due

   £4,750 .00

   On taxable total profits of £25,000 at 19.0% · small profits

   Why 19%

   The profit limits are reduced to the 1 April 2025 to 31 December 2025 dates, and £25,000 is still below the reduced lower limit.GOV.UK: Corporation Tax rates

   Optional

   Click Preview your documents (free) and check the dates on the CT600, the computation and the accounts

   Subscribe

   Click Unlock Filing and complete payment

   Continue

   Click Continue to submission

5. Filing credentials

   Corporation Tax UTR

   Your 10-digit UTR

   Gateway User ID

   Your Government Gateway user ID

   Gateway Password

   Your Government Gateway password

   Select the director submitting this return

   The director’s name

   Accounts approval date

   The date the directors approved the accountsWhat to enter

   Declaration

   Tick it

   Click Submit to HMRC.

   More help: If HMRC rejects your sign-in details

6. After you submit

   Under Gateway submissions, the filing page lists the return for 1 April 2025 to 31 December 2025. It shows Accepted once HMRC confirms it. HMRC usually replies within a few minutes, but it can take longer.

   The payment deadline follows the Corporation Tax period end, not the accounts end. The Review & file page shows the dates.

   More help: Payment and filing dates explained · Paying your Corporation Tax

Sample outcome

1. How your figures are treated (Enter my figures once)

Beside the dates, the wizard states which period the main figures cover. Dates before or after the accounts have their own additional-figures section on Financial Data.

Corporation Tax period inside the accounts

Main Profit & loss and Tax adjustments entries

For a later tax start after a period without trading, enter the full approved accounts figures, including earlier costs. For an earlier tax end, the attached accounts profit and loss shows only the entered CT-period figures.

Corporation Tax period starts earlier or ends later

Main Profit & loss entries

Use the full statutory accounts period here.

Additional dates before the accounts

Days before your accounts start → Any income, expenses or other tax figures for these dates?

Answer No if none. Answer Yes to enter the additional amounts separately. If those dates cross a return boundary, complete the split beneath them.

Additional dates after the accounts

Days after your accounts end → Any income, expenses or other tax figures for these dates?

This section follows the main Profit & loss entries. Enter only the additional dates shown. Confirm the split if they cross a return boundary.

Closing assets, liabilities and comparatives

Balance sheet and prior-year columns

Use the statutory accounts dates. These do not become balances at the shorter CT-period end.

For a later Corporation Tax start after a period without trading, enter the figures from the full approved accounts, including costs from before the tax start. Do not also claim those costs in Qualifying pre-trading expenditure. Read which accounts go with the first CT600. If Corporation Tax ends before the accounts end, enter the tax-period figures. We use the amounts as entered without reducing them for the shorter span. The attached accounts profit and loss will then omit activity after that tax end, while the balance sheet stays at the accounts end.

With accounts covering January to December and tax ending in September, £60,000 turnover and £12,000 expenses entered for that CT period remain £60,000 and £12,000 in the tax inputs and attached profit and loss. The profit and loss will not show October to December activity. The balance sheet remains at the December accounts end.

Balance-sheet figures are different: they remain balances at the statutory accounts end. Existing rules for qualifying pre-trading expenditure, dated transactions and brought-forward amounts still apply. Short-period tax limits and any financial-year or two-return calculations also continue.

When Corporation Tax starts before the accounts

Enter your main profit and loss figures for the full statutory accounts period. In Financial Data, answer “Any income, expenses or other tax figures for these dates?” (or “for this day?” for a single date) under Days before your accounts start. Choose No if there are no additional figures. Choose Yes to enter them separately.

After Yes, open “How these figures are used” for the explanation. Each amount has an information icon with help about what to include and exclude. Use only the additional dates shown at the top of this section.

For example, accounts from 2 January to 31 December and a CT period from 1 January to 31 December have one additional day. Statutory turnover of £10,000 and additional trading income of £500 produce £10,000 statutory turnover and £10,500 trading income in the tax computation.

Trading expenses exclude depreciation and amortisation, which have their own field. Open the property or tax-adjustment section only when relevant. These additional figures do not alter your statutory operating figures, comparatives or balance-sheet inputs. The accounts tax line follows the Corporation Tax due on the return, less any entered Corporation Tax recoverable, so profit after tax can change.

If there are two CT600s, ordinary accounts figures follow the days each return covers within the accounts period. Additional figures belong to their own dates. If those dates cross the return boundary, enter and confirm the split immediately below the additional figures. Date edits remain drafts for you to review before submission.

When Corporation Tax ends after the accounts

Keep the main Profit & loss figures for the full statutory accounts period. Below them, under Days after your accounts end, answer the question about additional income, expenses or tax figures. Choose No if there are none. Choose Yes and enter only the dates displayed in that section.

For example, accounts for 1 January to 31 December 2025 with £10,000 turnover and coverage ending 31 January 2026 can have £1,000 additional January turnover. The statutory turnover stays £10,000. The first return uses £10,000 and the second uses £1,000. The accounts tax charge continues to follow the returns, less any entered Corporation Tax recoverable.

If the additional dates cross the return boundary, enter and confirm their split. For accounts ending 30 November 2025 and coverage from 1 January 2025 to 31 January 2026, the extra dates cover December and January. £600 in December and £400 in January means a £600 and £400 split. The displayed return dates follow First CT600 ends. Check both returns before confirming the allocation. Longer statutory accounts use the same controls.

Beside the dates, we state which period the main figures cover. This is guidance rather than an additional checkbox because you make the correctness and completeness declaration before filing with HMRC.

2. Date rules

• Keep the full annual accounts period under Accounting period. Do not shorten the accounts dates to make the CT600 fit.
• Both Corporation Tax period start and Corporation Tax period end are required.
• If the tax start is earlier than the accounts start, use the same end date as the accounts. Otherwise the tax start must be within the accounts period and the end may be later.
• The tax end must be on or after the tax start and cannot be in the future.
• The Corporation Tax dates must overlap the accounts and fit within two returns of at most 12 months each.
• Changing either tax date unticks the confirmations, so read and tick them again for the new dates.

For example, accounts might cover 1 January to 31 December 2025 while the confirmed tax period covers 1 April to 30 September 2025. Enter the full accounts pair first and the shorter tax pair second.

The page asks you to confirm that the dates match your CT603 notice or HMRC business tax account. It also asks you to confirm the company's position between the accounts start and a later Corporation Tax start. These checks support the date selection. They do not determine whether an earlier end is legally correct. HMRC sets out the events that end a tax period.

If you believe HMRC's dates are wrong, call HMRC to resolve them before filing and use the dates it confirms. Do not change dates in filing software to override an unresolved HMRC record. HMRC explains how notice dates and return periods can differ.

3. Corporation Tax dates over 12 months

A Corporation Tax accounting period cannot be longer than 12 months. When the Corporation Tax dates you enter end more than 12 months after they start, even by one day, the preview shows two Corporation Tax returns. The first covers 12 months from your Corporation Tax start and the second covers the rest. Your accounts period itself can be up to 18 months.

• If HMRC's first period ends on a different day, open Change CT600 split date and set First CT600 ends to the end HMRC shows. The second return starts the next day and neither return may exceed 12 months. Match your two CT600 dates to HMRC
• With Enter my figures once, recurring income and expenses are shared between the two returns by the number of days in each. Amounts that belong to one date, such as dividends, gains and capital purchases, follow the split you confirm on the allocation panel. Amounts that belong to one date
• Each return gets its own profit limits, reduced for a return shorter than 12 months, its own computation and its own payment deadline.

4. Check the documents before filing

Continue through the financial step, then choose “Review filing” to save your answers and prepare the review. Check the documents before submitting to HMRC.

• The CT600 and tax computation should show the selected tax dates, or the individual return dates where the span splits.
• The attached accounts should show the statutory period dates and balance-sheet date. For an earlier tax end, the generated profit and loss includes only the entered CT-period figures, so it can differ from the company's approved full-period accounts.
• The CT600 accounts indicator should reflect its attachment. Different accounts dates use box 85. A second return wholly after the accounts uses box 90 with the reason that the accounts were sent with the other return. See HMRC's CT600 instructions.
• Check payment and filing dates separately. See the deadline explanation.

5. If you cannot continue

I cannot see the separate-date option.

Check the filing choice. It appears when What are you filing? is HMRC CT600 or Companies House & HMRC CT600. It is absent for Companies House-only filing. To file both together with different tax dates, choose Enter figures separately. With Enter my figures once, choose HMRC CT600 and file the Companies House accounts separately. A filing made elsewhere can use it with Amend both CT600 returns, Amend the first CT600 and file the second as new, or File the first CT600 as new and amend the second. Amend only the second CT600 instead uses First CT600 ends to set the remaining start. An amendment of a filing made through this service keeps its original dates.

The wizard says to choose Enter figures separately.

The message reads “To send accounts to Companies House with different Corporation Tax dates, choose Enter figures separately, or file to HMRC only.” It appears when Companies House & HMRC CT600 is combined with Enter my figures once. Choose Enter figures separately, or choose HMRC CT600 and file the accounts at Companies House separately.

The tax estimate disappeared.

Complete both tax dates and correct any range error. An incomplete pair cannot produce a current preview.

My confirmations became unticked.

Changing period dates withdraws the confirmations. Read and confirm them again for the new dates.

The tax end changed after I edited the accounts end.

An end that matched the previous accounts end follows the new accounts end. An explicitly different end is preserved. Check the displayed dates and review the additional figures again.

I unticked the box by mistake.

Unticking it after entering a start date asks you to confirm, because it clears the Corporation Tax dates and the confirmations. Tick it again and re-enter them.

How do I save my changed dates?

Choose “Review filing” after completing the steps. Once the company is added, “Save Progress”, “Next” and “Back” save your unfinished form to your account. Check for “Saved to your account” before closing the page. Changes after your last save stay only in that browser tab.

If you shorten the accounts period on a filed-elsewhere amendment, separate Corporation Tax dates you have entered stay visible. Correct those dates and tick the withdrawn confirmations again. To use the accounts dates instead, untick this box: My HMRC Corporation Tax period is different from my statutory accounts period.

Amending this return later

If you filed the CT600 with different dates through this service, its amendment keeps the original accounts dates, Corporation Tax dates and first CT600 end. A span over 12 months regenerates both returns. Follow the amendment steps. An amendment cannot move the dates of a return HMRC already holds. If a filed return has the wrong dates

For a filing made elsewhere, Amend both CT600 returns and Amend the first CT600 and file the second as new accept separate Corporation Tax dates and a custom first end. To amend only the remaining period, follow the second CT600 amendment guide.

Not the right option?

Open the guide for the option that matches your filings.

Looking for a different field or step? See all filing wizard guides →

Official sources

• GOV.UK: Corporation Tax accounting periods
• GOV.UK: Corporation Tax rates
• HMRC Company Tax Return guide: boxes 80, 85 and 90
• HMRC CTM93020: notice periods and return periods
• HMRC CTM01500: when an accounting period ends
• HMRC CTM93180: accounts to deliver with the return
• HMRC: active and dormant for Corporation Tax

This describes the supported SimpleCompanyTax#Simple CompanyTax workflow. It is general guidance, not a determination of your company's tax periods or entitlement to relief.

If only the second CT600 has been filed and the first is still outstanding, file the first CT600 as new and amend the second. That route sends both returns and includes the full accounts, rather than leaving the first unchanged.