Think you’ve overpaid tax in a previous year? You might be able to claim it back through the HMRC overpayment relief claim process but there’s a catch – a strict time limit.

And once that passes, the money stays with HMRC. Many people only discover errors years later – often when switching accountants or reviewing old returns.

But if the deadline’s gone, even a clear-cut case may be rejected. This guide explains what overpayment relief is, who it applies to, and – most importantly – when the clock runs out.

Key takeaways: Overpayment relief claim time limit

  • Overpayment relief is a formal way to reclaim tax paid in error
  • The time limit is four years from the end of the relevant tax year
  • Claims must be detailed, evidenced, and submitted in writing
  • You can’t use the standard online Self Assessment process
  • After the deadline, HMRC won’t process your claim

What is an overpayment relief claim?

Overpayment relief is how you reclaim tax that you paid in error – usually due to a mistak or excessive assessment e in a tax return that can no longer be amended.

It’s not for minor adjustments or last-minute tweaks. It’s used when the normal window for making changes has passed, and there’s no active appeal or ongoing enquiry. In other words, it’s a fallback – not your first option.

Self-employed individuals, landlords, or those with multiple income sources often use overpayment relief when spotting older errors. That might be a misreported gain, a missed allowance, or tax paid on income that wasn’t taxable.

If you’ve run out of other ways to correct the mistake, overpayment relief could be your last shot at getting your money back.

Who can make a claim – and when?

Anyone who’s paid too much tax because of a genuine mistake can apply, as long as certain conditions are met.

First, there must be no other option available. If you can still amend your return or submit an appeal, HMRC expects you to go through that route. Overpayment relief only applies when those doors have closed – typically after the one-year amendment window ends.

You’ll also need to prove the overpayment wasn’t due to carelessness, fraud or a failure to take reasonable care. HMRC wants to see why the tax was wrong, how the correct figures were worked out, and what evidence backs it up. It’s not enough to say, “I think I paid too much” – you need to show it.

Examples of when overpayment relief might apply include incorrect capital gains figures, double-counted income, or a missed claim for relief. In each case, the claim needs to be clearly explained and fully supported.

If you’re not sure whether you qualify, or whether overpayment relief is even the right route, it’s worth speaking to an accountant.

Timing is critical – because even if your claim is valid, HMRC won’t accept it if you miss the deadline.

What is the HMRC overpayment relief claim time limit?

HMRC’s overpayment relief claim time limit is four years from the end of the tax year in which the error happened.

This is key: it’s not four years from when you discover the mistake. It’s counted from the tax year itself.

Example

If the mistake was made in your 2021/22 tax return, which ended on 5 April 2021, then your claim must be received by HMRC no later than 5 April 2026.

Miss that deadline, and HMRC won’t consider the claim – even if the overpayment is obvious and well-documented.

They do not make exceptions for lack of awareness, illness, or delays in discovering the mistake.

How to make an HMRC overpayment relief claim

Overpayment relief claims aren’t something you can sort out with a quick online form. They must be made in writing and follow a strict format.

Your written claim should include:

  • The tax year in question
  • A full explanation of the mistake and why too much tax was paid
  • Revised calculations and supporting documents
  • A clear statement that the claim is being made under overpayment relief rules
  • A confirmation that no other claim route (e.g. appeal or amendment) is available

You’ll also need to include your name, National Insurance number or Unique Taxpayer Reference (UTR), contact details and signature.

It’s a formal process, and HMRC expects claims to be thorough. Submitting an incomplete or unclear letter could lead to rejection. This is where using a professional accountant can save time and reduce risk.

Why timing matters

Let’s say your new accountant discovers that you overpaid tax in your 2018/19 return. The figures are clear, and the overpayment is supported by solid evidence.

But if you’re now in August 2025, it’s too late – the deadline to claim passed on 5 April 2023. Even if HMRC agrees you paid too much, they won’t issue a refund.

That’s why it’s worth reviewing past returns sooner rather than later. You might still be in time to recover money you didn’t realise was lost.

Filing your tax return late – or missing the payment deadline – can land you with some hefty self assessment late payment penalties from HMRC. 

FAQs: Overpayment relief claims

What is the time limit for HMRC overpayment relief?

You have four years from the end of the relevant tax year to submit your claim. HMRC won’t accept late applications, no matter the reason.

How many years back can I claim overpaid tax?

You can go back up to four tax years. So during the 2024/26 tax year, you can claim for 2021/22, 2022/23, 2023/24 and 2024/25.

What is the 6-year rule for HMRC?

This rule applies to HMRC pursuing unpaid tax through carelessness, not refund claims. It doesn’t affect overpayment relief, which is limited to four years for taxpayers claiming money back.

How many years can HMRC go back to claim taxes?

HMRC can look back up to 20 years in some cases – such as where deliberate fraud is involved. But when it comes to refunds via overpayment relief, the time limit is four years.

What happens if you miss the overpayment relief deadline?

Your claim will be rejected. HMRC doesn’t allow extensions or exceptions once the four-year limit has passed.

Can I claim interest on tax I overpaid?

Yes – if HMRC accepts your claim, they may also pay repayment interest.

Final thoughts: HMRC overpayment relief claims

We hope you found this article useful. Our blog is full of helpful guides and information – some of our most popular articles include:

Overpaying tax is frustrating enough. But finding out you’ve missed the deadline to reclaim it is even worse.

Overpayment relief gives you a second chance – but only if you act in time. If you think there’s a mistake in a previous return, don’t wait.

Here at Accountants East London, we help individuals and business owners spot overpayments and submit claims correctly.

We’ll review your previous tax years and let you know if you’re still within the claim window.

If you think HMRC owes you, let’s find out before the clock runs out. Why not contact us today?