Scope: This guide helps individuals choose the official HMRC route when they may have paid too much UK Income Tax. It does not calculate an entitlement or promise that HMRC will issue a repayment.
The short answer
Start with HMRC’s tax-refund route checker. The route depends on what the possible overpayment relates to: pay from a job, employment expenses, a pension, Self Assessment, redundancy or another income category listed by HMRC. The checker identifies the next service or guidance; it does not itself submit a claim.
After the tax year ends, an employee or pension recipient may receive a P800 if HMRC calculates that too much or too little tax was paid. HMRC may issue a Simple Assessment where tax is owed and cannot be taken automatically, more than £3,000 is owed, or tax is due on the State Pension. Someone registered for Self Assessment will have an overpayment or underpayment adjusted through that system and will not receive either of those letters for the adjustment.
Choose the route before sending information
“Tax refund” covers several different processes. Using a form intended for job expenses when the possible overpayment arose through a Self Assessment return can delay matters or create duplicate contact. Identify the income source and tax process first.
| Possible reason for overpayment | First official step |
|---|---|
| PAYE deducted from employment pay | Use HMRC’s refund checker and select pay from a job. |
| Employment costs such as eligible work clothing, tools or travel expenses | Select job expenses in the checker. Do not assume every cost qualifies. |
| Tax deducted from a pension or annuity | Select the matching pension or annuity category. |
| An amount shown through Self Assessment | Use the Self Assessment route identified by HMRC. |
| Redundancy pay | Select redundancy payment so that the correct guidance is shown. |
| UK income while living abroad, foreign income, savings interest or UK income before leaving | Select the precise category in the checker rather than treating it as an ordinary PAYE claim. |
These categories describe how HMRC routes a possible claim, not a finding that a refund is due.
If HMRC sends a P800 or Simple Assessment
After the tax year ends, HMRC may send an employee or pension recipient a P800 if its calculation shows too much or too little tax was paid. A Simple Assessment is used where tax is owed and cannot be taken automatically, more than £3,000 is owed, or tax is due on the State Pension. The communication explains the action to take. Check that the income, tax deducted and other details shown belong to the correct year before following that action.
Use the instructions in the genuine HMRC communication or sign in through GOV.UK independently. A message saying “tax refund available” is not enough evidence that money is due. Do not give personal or bank details to an unverified caller or a link in an unexpected message.
P800 example
Sam had two PAYE jobs during the year and later receives a P800. Sam compares the employments and tax deducted on the calculation with the available P45s and payslips. If the figures agree, Sam follows the refund instructions in the calculation. If an employment or amount is wrong, Sam resolves that discrepancy before treating the result as final.
This example is about checking the route and source data. It does not predict Sam’s refund.
If a Self Assessment return is involved
A person registered for Self Assessment normally has an overpayment or underpayment adjusted through Self Assessment. That is different from waiting for an employee or pension P800.
Check the submitted return, the tax calculation and the Self Assessment account. If a return contains an error, use the appropriate correction or amendment process rather than starting an unrelated PAYE-expense claim. A repayment shown in the account may still be subject to HMRC checks.
Self Assessment example
Aisha submits a return that includes self-employment income and tax already deducted from another source. Her calculation shows an overpayment. Because she is registered for Self Assessment, she checks the repayment position in that process instead of waiting for a P800.
The example does not establish how much is repayable or how long a check will take.
Information to assemble first
Collect only the records relevant to the route, which may include:
- the tax year or years concerned;
- payslips, P45s, P60s or pension statements;
- the P800 or Simple Assessment, if one was issued;
- the submitted Self Assessment return and calculation, if applicable;
- records supporting the particular expense or income category; and
- HMRC reference details shown in the official account or correspondence.
Do not send original documents unless the official route specifically requires them. Keep a copy of what was submitted and a record of the date and channel used.
Common mistakes to avoid
- Treating every lower-than-expected payslip as proof of an annual overpayment.
- Using the job-expense route for a Self Assessment repayment.
- Claiming the same item through more than one route.
- Assuming a P800 will be issued to someone whose adjustment belongs in Self Assessment.
- Paying a company to submit a claim before checking the free official route.
- Sharing sign-in, bank or identity information through an unverified message.
What to do next
- Identify exactly what the suspected overpayment relates to.
- Use the official HMRC refund checker; it identifies the route but does not submit the claim.
- If a P800 or Simple Assessment exists, check its underlying figures and follow its instructions.
- If registered for Self Assessment, check the return, calculation and account first.
- Keep copies of records, calculations and correspondence.
- If PAYE coding caused the issue, understand the tax code before asking HMRC to change its underlying details.