Two CT600s with different dates from HMRC: how to match them

1. Before you start

Have the full accounts dates, both HMRC return periods and your prepared figures ready. A CT600 reports a Corporation Tax accounting period. Your statutory accounts can cover a longer period, so these are different date pairs. If HMRC's records look wrong, resolve the dates with HMRC before filing.

A shorter first period can be correct. Read when a Corporation Tax accounting period ends for the events that can cause it. The software uses the dates you enter and does not determine which event applied.

2. Enter the dates

1. In the company wizard, set Period start and Period end to the full statutory accounts period. A club or charitable association uses the accounts date fields on its own wizard.
2. For an ordinary company, if the Corporation Tax span differs, choose the supported HMRC-only route and select My HMRC Corporation Tax period is different from my statutory accounts period. Enter both Corporation Tax dates and complete the existing confirmations. See the separate-date steps.
3. For a span producing two CT600s, the standard return dates are calculated for you. Leave them as they are if they match HMRC. Only if the first end differs, open Change CT600 split date beside the dates and enter the first period end in First CT600 ends. Check the displayed start and end of each return.
4. Enter recurring income and expenses once for the period the wizard specifies. They are shared by days using the displayed return dates. Amounts shown on an allocation panel follow the allocation you enter and confirm. A one-off box 205 receipt can appear in both returns. See other income in CT600 box 205. Do not divide figures yourself and then enter the divided total.
5. If you change an accounts or Corporation Tax date, check the displayed return dates again. The split resets to the default. Open Change CT600 split date again only if HMRC shows a different first end. Review and confirm any allocation whose return dates changed.

If the field shows an error, correct that date. It stays visible. An end outside the span, a first return over 12 months or a second return over 12 months cannot be saved as a valid split.

If you shorten an accounts period on a filed-elsewhere amendment, any separate Corporation Tax dates you have entered stay visible. Check those dates and tick the confirmations again, or untick My HMRC Corporation Tax period is different from my statutory accounts period to use the accounts dates.

3. Original and amended returns

• Original filing: both CT600s use your selected boundary and are new returns.
• Amend both CT600 returns: choose Amend filing made elsewhere, thenHMRC CT600 under What are you filing?and this choice under Filing purpose. Enter the full accounts dates, any separate Corporation Tax dates and the first return end. Both CT600s are amended.
• First CT600 already filed, second not yet filed: choose this under Filing purpose after Amend filing made elsewhereand HMRC CT600 under What are you filing?. Enter the full-period figures once. The first CT600 is amended and the second is new, using the two displayed periods.
• File only the remaining CT600: set First CT600 ends to the end of the first CT600. The remaining period starts the next day. Enter only its figures and complete the existing confirmation about accounts accompanying the earlier filing. Follow the remaining-return guide.
• Amend a filing made through this service: the original date is shown read-only. The amendment keeps that filing's periods.

First CT600 ends is also available for a supported long-period ordinary club, CASC or charitable association. Complete the existing treatment and allocation questions for both returns. Charity companies use the accounts dates with First CT600 ends. They do not use separate Corporation Tax dates or the remaining-only purpose.

4. Worked example

Fictional Willow Example Ltd has accounts from 1 August 2024 to 30 September 2025. Its HMRC periods are 1 August 2024 to 31 March 2025 and 1 April to 30 September 2025. Enter 31 March 2025 in First CT600 ends.

The periods have 243 and 183 days, totalling 426 days. £42,600 of recurring income is shared as £24,300 and £18,300. A £1,000 capital allowance belonging to the second return is allocated £0 and £1,000. It is not shared by days.

5. Check both returns

Choose Preview your documents (free), then Generate draft preview →. Check both CT600s and computations before filing. Boxes 30 and 35 should show each return's selected dates. Check each computation's period, recurring figures and confirmed allocations. The attached accounts retain their statutory dates. Where they differ from the return, box 85 (Different period accounts) reflects that difference.

This is general guidance for the supported SimpleCompanyTax#Simple CompanyTaxworkflow. Use the dates, figures and tax treatments prepared for your organisation.

Official sources

• GOV.UK: Accounting periods for Corporation Tax
• CTA 2009 section 9: beginning of an accounting period and section 10: end of an accounting period
• HMRC CTM01510: accounts covering more than 12 months
• HMRC CTM01405: time apportionment
• HMRC: Company Tax Return guide