HMRC Tax Refund Deadline: How Far Back Can You Claim?
Learn about the 4-year deadline for claiming tax refunds from HMRC. Find out which tax years you can still claim for in 2026 and how to avoid losing money to expired claims.
One of the most important things to know about tax refunds in the UK is that there is a deadline. You cannot go back indefinitely and claim money that HMRC owes you. The general rule is 4 years, but the details matter. If you do not understand the deadline, you could miss out on money that is rightfully yours.
The 4-Year Rule
Under UK tax law, you can claim a refund of overpaid income tax for the current tax year and the previous 4 tax years. This is set out in the Taxes Management Act 1970 and applies to claims made under the PAYE regulations.
As of the 2025/26 tax year (which runs from 6 April 2025 to 5 April 2026), you can claim refunds going back to the 2021/22 tax year. Once the 2026/27 tax year begins on 6 April 2026, the 2021/22 year will drop out of the window and you will lose the right to claim for that year.
Which Tax Years Can You Claim in 2026?
Here is the current position:
| Tax Year | Dates | Can You Claim in 2025/26? |
|----------|-------|---------------------------|
| 2025/26 | 6 Apr 2025 - 5 Apr 2026 | Yes (current year) |
| 2024/25 | 6 Apr 2024 - 5 Apr 2025 | Yes |
| 2023/24 | 6 Apr 2023 - 5 Apr 2024 | Yes |
| 2022/23 | 6 Apr 2022 - 5 Apr 2023 | Yes |
| 2021/22 | 6 Apr 2021 - 5 Apr 2022 | Yes (last chance) |
| 2020/21 | 6 Apr 2020 - 5 Apr 2021 | No - deadline passed |
The critical one to note is 2021/22. If you have overpaid tax in that year, you need to make your claim before 5 April 2026 or the money is gone permanently.
How the Deadline Works in Practice
The deadline is based on when you submit your claim, not when HMRC processes it. So if you post a letter on 4 April 2026 claiming a refund for 2021/22, the claim is valid as long as it arrives within a reasonable time. However, do not leave it until the last minute. If there are any postal delays or issues, you could miss the deadline.
For phone claims, the date of the call counts. For online claims through your Personal Tax Account, the date you submit counts.
What Counts as a Valid Claim?
A valid claim for a PAYE refund can be:
- A phone call to HMRC's PAYE helpline (0300 200 3300) requesting a review of a specific tax year
- A letter to HMRC setting out the overpayment with supporting figures
- A claim submitted through your online Personal Tax Account
- A formal PAYE reconciliation request
When making the claim, you need to specify which tax year you are querying and provide evidence of the overpayment. At minimum, you should reference your total income and total tax paid for that year (from your P60 or P45) and explain why you believe the tax deducted was too much.
AuditMyTax can generate a detailed reconciliation letter that sets out all the relevant figures and calculations, which makes the claim process much smoother.
Are There Any Exceptions to the 4-Year Rule?
In limited circumstances, you may be able to claim beyond the 4-year window:
**HMRC error:** If the overpayment was caused entirely by HMRC's mistake (not yours and not your employer's), HMRC has the discretion to refund beyond 4 years under their Extra-Statutory Concession B41. However, this is applied sparingly and you would need to show that the error was clearly HMRC's fault and that you could not reasonably have been expected to notice the overpayment at the time.
**Deceased persons:** Different rules can apply when claiming on behalf of someone who has died. The personal representative should contact HMRC directly for guidance.
**Court orders or tribunal decisions:** In rare cases, a tax tribunal may order HMRC to make a refund outside the normal time limits.
For the vast majority of people, the 4-year rule is absolute. Do not rely on exceptions.
How to Check Multiple Years Efficiently
If you want to check whether you have overpaid in any of the years still within the window, here is a practical approach:
1. **Gather your P60s** for each year (or P45s if you left jobs during those years). If you do not have them, check your HMRC Personal Tax Account online, or ask former employers for copies.
2. **Check each year individually.** The tax bands and Personal Allowance are different for each year, so you need to check each one against the correct figures. The Personal Allowance has been 12,570 pounds since 2021/22, so the calculation is consistent across recent years.
3. **Use a calculator.** Rather than doing the maths manually for 5 years, use AuditMyTax to check each year. Upload the relevant document and it will tell you whether you have overpaid.
4. **Submit claims for all relevant years at once.** If you are owed refunds for multiple years, you can submit claims for all of them together. HMRC will process each year separately, but submitting them at the same time is more efficient.
Do Not Wait for HMRC
HMRC may send you a P800 tax calculation if they identify an overpayment, but they do not guarantee catching every discrepancy. Many people assume that if HMRC has not contacted them, their tax must be correct. This is not always the case.
Take responsibility for checking your own tax. The 4-year window means there is always urgency for the oldest year in the window. Right now, 2021/22 is your last chance. If you have any P60s or P45s from that year, check them before April 2026.
Key Takeaways
The 4-year deadline is real and enforced. Every April, one more tax year falls out of the window and the money is gone. If you have changed jobs, been on the wrong tax code, or worked multiple jobs in any of the last 5 tax years, spend a few minutes checking each year. The potential refund across multiple years could be substantial, and once the deadline passes, there is no getting it back.