Guidance

Check if you should claim overpayment relief for Corporation Tax

If you believe you’ve overpaid tax, use the tool to tell you if an overpayment relief claim is the correct way for you to claim it back.

If you believe your company has overpaid Corporation Tax you may claim overpayment relief.

The ‘check if you should make a claim’ tool in this guide is for agents and companies.

The tool:

  • tells you how to claim
  • explains why your claim for overpayment relief may not be successful

Who can claim

You can only claim if (for the accounting period you’re claiming for) you’ve:

  • paid Corporation Tax
  • been assessed to pay Corporation Tax

Agents cannot make an overpayment relief claim on behalf of a company.

We will reject your claim if a listed exclusion (HMRC manual SACM12070) applies to you.

When can you claim

The time limit for claiming is 4 years from the end of the relevant accounting period. Find out how to determine the relevant accounting period (HMRC manual SACM12155).

Your accounting period is the time covered by the Company Tax Return.

Read about how HMRC considers late claims (HMRC manual SACM10040).

What you need

To use the tool you’ll need to tell us:

  • the end date of the accounting period you made the mistake in
  • if you paid Corporation Tax for this period
  • if you’ve been assessed to pay Corporation Tax for this period
  • if you under-declared a loss
  • if you submitted a return
  • if you think any exclusions apply
  • if other accounting periods were impacted — for example, an under-declared loss was carried forward into the next accounting period

Check if you should make a claim

Use the tool to find out if you should make a claim for Corporation Tax overpayment relief.

Check now

If you make a claim

You must submit a claim in this format (HMRC manual SACM12150).

If you do not make a correct claim you risk rejection, delays and missing deadlines for claiming. To avoid errors review the overpayment relief manual SACM1200.

HMRC may open an enquiry into your claim and ask you for evidence to support it such as:

  • documentary proof of the tax deduction
  • evidence of the tax being suffered in some other way

Updates to this page

Published 9 September 2025

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