HMRC Overpayment Relief Claim
How to reclaim tax you should not have paid
Have you discovered a mistake in an earlier tax return or realised that HMRC has assessed too much tax? You may still be able to recover the money, even after the normal amendment deadline has passed.
Overpayment relief is a statutory procedure for requesting repayment or cancellation of Income Tax, Capital Gains Tax or Corporation Tax that was not legally due. A valid claim is normally required within four years of the end of the relevant tax year or accounting period, and specific exclusions apply.
What is an HMRC overpayment relief claim?
An overpayment relief claim is a formal request asking HM Revenue & Customs to repay tax, or cancel an excessive tax liability, where the amount was not legally due.
It is particularly relevant where a taxpayer discovers an error after the normal deadline for amending a Self Assessment or Company Tax Return has expired.
The principal statutory provisions are Schedule 1AB to the Taxes Management Act 1970 for Income Tax and Capital Gains Tax, and paragraph 51 of Schedule 18 to the Finance Act 1998 for Corporation Tax.
Personal tax mistakes
Errors in taxable income, allowable expenses or the calculation of Income Tax may lead to an excessive liability.
Incorrect gains
A calculation error, incorrect base cost or overlooked allowable expenditure may result in too much CGT being paid.
Company tax errors
A company may have overstated taxable profits or understated allowable deductions, subject to the statutory restrictions.
Who can claim overpayment relief?
Individuals, businesses and companies may qualify where they have paid, or been assessed to pay, more relevant tax than was legally due.
Before submitting a claim, consider these questions:
Was tax excessive?
Identify a genuine error in the amount of tax calculated or assessed, supported by the applicable tax rules.
Is the claim in time?
Check the four-year statutory deadline using the correct tax year or company accounting period.
Does an exclusion apply?
Consider whether the claim is restricted by legislation, an earlier decision, an available alternative remedy or another exclusion.
Common reasons for overpaid tax
Examples include an arithmetical error in a return, incorrect treatment of an allowable business expense, overstated taxable receipts, or an incorrect Capital Gains Tax calculation.
However, the discovery of a missed deduction or relief does not automatically establish entitlement. Some claims are excluded, particularly where the law required a separate claim or election within its own time limit.
Overpayment relief vs amending a tax return
One of the most common mistakes is attempting to make an overpayment relief claim when the correct procedure is to amend an existing return.
| Feature | Tax return amendment | Overpayment relief claim |
|---|---|---|
| Purpose | Correct an existing return | Recover or discharge excessive tax under statutory relief provisions |
| Typical timing | Within the normal amendment period | Often after the amendment period has closed |
| Self Assessment deadline | Normally 12 months after the filing deadline | Normally four years after the relevant tax year ends |
| Method | Amended tax return | Separate written claim |
| Restrictions | Return amendment rules | Specific statutory exclusions and conditions |
For example, the normal amendment deadline for a 2024/25 Self Assessment return is 31 January 2027. If that deadline has passed, a qualifying overpayment relief claim may still be possible until 5 April 2029.
For companies, the normal CT600 amendment window is generally 12 months after the statutory filing date, with separate overpayment relief provisions potentially applying afterwards.
Read our related guides on amending a tax return and CT600 Corporation Tax Returns.
HMRC overpayment relief deadline checker
Enter the relevant tax year or company accounting period end to calculate the ordinary four-year claim deadline. The checker uses the statutory period-end rule rather than the date on which the mistake was discovered.
Check your four-year deadline
This calculator provides the normal statutory deadline only. Special provisions, exclusions, unusual accounting periods and claims involving earlier-period losses require individual review. It does not determine eligibility.
Examples of the four-year deadline
| Relevant period | Ordinary claim deadline |
|---|---|
| 2021/22 tax year | 5 April 2026 |
| 2022/23 tax year | 5 April 2027 |
| 2023/24 tax year | 5 April 2028 |
| 2024/25 tax year | 5 April 2029 |
| Company period ending 31 March 2024 | 31 March 2028 |
How to make an HMRC overpayment relief claim
Identify the tax error
Review the original tax return, assessment and supporting calculations. Explain precisely why the tax was not due.
Recalculate the correct liability
Prepare a reconciliation showing the original liability, corrected liability and amount claimed. Retain supporting working papers.
Check the statutory deadline and exclusions
Establish the relevant tax year or accounting period. Review whether a claim or election was missed and whether any statutory exclusion prevents relief.
Prepare a standalone written claim
Identify the claimant, relevant period, grounds for relief, amount claimed and whether there has been a previous appeal. Include the required declaration.
Arrange the correct signature
An individual must sign their own claim. A company claim must be signed by an officer of the company. A tax agent cannot sign the declaration instead of the claimant.
Submit the claim and retain evidence
Send the written claim to the appropriate HMRC department. Keep a complete copy, supporting evidence and proof of posting.
Respond to HMRC enquiries
HMRC may request further information, examine the legal basis or open an enquiry. A repayment is not automatic merely because the claim has been submitted.
Where should you send the claim?
PAYE Self-Assessment
HM Revenue and Customs
BX9 1AS
Corporation Tax Services
HM Revenue and Customs
BX9 1AX
These are the postal addresses stated in HMRC's overpayment relief guidance at the time of this update. Check the current address before posting.
HMRC overpayment relief claim letter generator
Use this tool to prepare a draft claim letter containing the key information HMRC expects. It generates text locally in your browser; your details are not submitted to The Online Accountants by this tool.
Prepare your claim letter
Drafting aid only. This is not a submission to HMRC and does not establish that a claim is valid. Review the grounds, calculations, exclusions and supporting documents before signing. Do not send the draft with unresolved placeholders.
Examples of when overpayment relief may apply
Example 1: Sole trader with an incorrect expense calculation
A sole trader discovers that an arithmetic error in the 2022/23 Self Assessment return overstated taxable profits by £5,000. The normal amendment period has closed.
If the corrected calculation establishes that £1,000 of Income Tax was not due, the taxpayer may consider a standalone overpayment relief claim before 5 April 2027, subject to the statutory conditions.
Key point: The calculation and supporting records matter as much as the claimed refund.
Example 2: Limited company with overstated profits
A company with an accounting period ending 31 March 2024 identifies a genuine computational error that caused taxable profits to be overstated.
Where the normal Company Tax Return amendment period has closed, the company may be able to make an overpayment relief claim by 31 March 2028.
Key point: A company officer must sign the declaration. Particular care is required where losses, earlier accounting periods or missed relief claims are involved.
Example 3: Capital Gains Tax calculation error
An individual discovers that allowable acquisition costs were incorrectly entered in a historic Capital Gains Tax computation, causing an excessive taxable gain.
Where the relevant conditions are met, a claim may be available within the four-year period.
Key point: The taxpayer must demonstrate the correct allowable costs and provide reliable supporting evidence.
Why might HMRC reject an overpayment relief claim?
Submitting a claim does not guarantee a refund. HMRC may refuse relief where the claim is outside the statutory time limit, is incomplete or falls within an exclusion.
| Potential problem | How to reduce the risk |
|---|---|
| Claim submitted too late | Calculate the relevant deadline before preparing the claim. |
| Missing claimant signature | Ensure the individual or appropriate company officer signs. |
| Unclear grounds | Explain the tax error and why the original liability was excessive. |
| No amount stated | Provide the exact repayment or discharge requested. |
| Insufficient evidence | Retain original records, revised calculations and proof of tax paid. |
| Statutory exclusion | Review the relevant exclusions before submission. |
| Claim made through a tax return | Use a separate written claim rather than entering it into the return. |
What happens if HMRC refuses the claim?
The available challenge depends on the reason for refusal. A dispute about entitlement may have statutory review or appeal routes, whereas HMRC's refusal to accept a late claim does not carry the same ordinary appeal right.
Review the decision notice carefully and obtain specialist advice promptly if HMRC disputes the legal basis of your claim.
Our guide to HMRC investigations explains what can happen when HMRC requests further records or examines tax calculations.
HMRC overpayment relief FAQs
How far back can I claim overpaid tax from HMRC?
Normally, an overpayment relief claim must be made within four years of the end of the relevant tax year or company accounting period. Different refund mechanisms and narrowly defined exceptions can have different rules.
Can I claim after the tax return amendment deadline?
Potentially, yes. Overpayment relief is a separate statutory procedure that may remain available after the normal amendment window closes, provided all its conditions are met.
Can my accountant submit an overpayment relief claim?
An accountant can assist with calculations, drafting and correspondence. However, the required declaration must be signed by the claimant or, for a company, an appropriate company officer. The tax agent cannot sign in their place.
Can I make an overpayment relief claim online?
HMRC requires a standalone written claim. It should not be included in a tax return. Follow the current HMRC submission guidance for the tax concerned.
Does HMRC pay interest on overpayment relief?
Repayment interest may arise under the relevant tax-specific rules, depending on the circumstances. It is not necessarily calculated from the date of the original mistake.
How long does HMRC take to process a claim?
There is no single guaranteed processing period. Claims requiring additional documents, technical consideration or an enquiry may take longer.
Can I claim for an overlooked tax relief?
Not always. Some missed claims and elections are specifically excluded. Whether overpayment relief is available depends on the statutory basis of the relief and the circumstances.
What evidence should I keep?
Retain original returns, assessments, tax payment evidence, corrected calculations, invoices, accounts and other records supporting the claimed amount.
Can a company claim overpaid Corporation Tax?
Yes, where the statutory conditions are met. The claim is subject to the Corporation Tax overpayment relief provisions, a normal four-year time limit and specific exclusions.
What if HMRC has issued an estimated tax determination?
Special provisions can apply to certain HMRC determinations, including exceptional rules for some otherwise out-of-time cases. These claims require careful consideration of the statutory conditions.
Related UK tax guides
Think you've paid too much tax?
Our ACCA-qualified accountants can help you understand your tax position, identify potential errors and consider the appropriate route for correcting historic liabilities.
We work with limited companies, sole traders and individuals throughout the UK. Any specialist overpayment relief work is subject to an agreed scope and fee.
Contact The Online Accountants →Prepared by The Online Accountants, a trading name of Parkinson (UK) Limited. Updated November 2026. This guide provides general UK tax information, not individual tax or legal advice. Legislation and HMRC procedures may change.