A timely warning for company tax returns
The deadline for filing a company’s corporation tax return with HMRC is 12 months after the end of the accounting period it covers. HMRC warns that it will charge a penalty if a return is not filed on time.
Online filing
Corporation tax returns can now only be filed online using commercial software, with HMRC having closed its free online corporation tax filing service on 31 March 2026:
- Any changes or amendments to previously submitted tax returns also have to be made using commercial software.
- HMRC no longer accepts amendments by letter.
HMRC publishes a list of commercial software suppliers for corporation tax. It makes sense to use software that will also file annual accounts with Companies House.
Paying corporation tax
Despite the 12-month tax return filing deadline, corporation tax usually needs to be paid nine months and one day after the end of the accounting period.
If it is not possible to file the return by this earlier deadline, an estimated payment can be made to minimise the amount of late payment interest which will be charged. The rate is currently set at 7.75%.
For a company with a 31 March 2026 year-end, the tax return is due by 31 March 2027. However, corporation tax will normally need to be paid by 1 January 2027, if late payment interest is to be avoided.
Loss relief claims
Should a corporation tax return involve the carry back of losses to a previous accounting period, HMRC has clarified that the correct treatment is to tick box 45 on the return to indicate that a repayment for an earlier accounting period is due.
A breakdown of the claim must then be included to show how losses have been used. There is no need to amend the return for the earlier accounting period.
HMRC’s list of commercial software suppliers for corporation tax can be found here.
