The Four-Year Refund Window: Reclaiming Overpaid Tax from 2022/23 Before April 2027
Many people assume that once a tax year has closed, the chance to correct it has gone. In practice, HMRC generally allows four years from the end of the tax year to claim a refund of overpaid income tax. For 2022/23, that four-year window ends on 5 April 2027. With 2026/27 now well under way, this is a sensible moment to check whether a past overpayment is sitting unclaimed.
The deadline is not a gentle administrative nicety. Once 5 April 2027 has passed, HMRC is generally unable to repay tax for 2022/23, even where the overpayment is obvious. The good news is that most claims are straightforward once you know what to look for.
Why 2022/23 still matters in 2026
The 2022/23 tax year ran from 6 April 2022 to 5 April 2023. It was a year of changing jobs, rising prices and, for many households, more than one source of income. Those factors can easily produce an incorrect tax code or an unclaimed relief. HMRC does not always spot the problem automatically, and a refund will not arrive simply because you were due one.
A common misconception is that a refund is available only if HMRC writes to you. That is not the case. You can review your own position and make a claim, provided you have reasonable evidence to support it.
Common reasons a refund may be due
Multiple jobs or a change of employment
If you had two jobs in 2022/23, or moved between employers, your personal allowance may have been split incorrectly. A new employer may have used an emergency tax code, or an old job may not have been removed from your tax code promptly. The result can be too much tax deducted through PAYE.
Check your P60s, P45s and final payslips for the year. If the tax deducted looks higher than it should, HMRC may be able to correct the code and issue a repayment.
Uniform, tools and mileage
Employees who must wear a uniform, maintain tools or use their own vehicle for work may be able to claim tax relief on qualifying expenses. For mileage, the usual approved rates are 45p per mile for the first 10,000 business miles and 25p thereafter, subject to the detailed rules. You cannot claim for ordinary commuting.
Flat-rate expense allowances also exist for some occupations, such as certain uniform roles. These are not automatic. You need to check that your job qualifies and that you have not already been reimbursed by your employer.
Pension contributions and professional subscriptions
If you made personal pension contributions and received basic-rate relief at source, higher or additional-rate relief may be due through self assessment or a claim to HMRC. Similarly, fees for approved professional subscriptions required for your job can sometimes be claimed.
Gift Aid donations and Marriage Allowance transfers are other areas worth reviewing, although they are not employment expenses. They can still reduce a tax bill or increase a refund for the year.
How to check before you claim
Start with HMRC's online personal tax account. It shows your employment history, tax codes and any self assessment records for the year. Compare that information with your own paperwork.
Gather the essentials before contacting HMRC: P60s, P45s, payslips, pension statements, receipts for expenses, mileage records and any letters from HMRC about your tax code. A claim is easier to make, and easier to defend, when the figures are supported by documents.
Do not claim a round sum simply because it feels about right. HMRC can inquire into claims, and careless or unsupported claims can lead to penalties. A modest, evidenced claim is better than an ambitious one that cannot be substantiated.
Claiming online or by post
For employment expenses, HMRC's online P87 service is often the quickest route where the total claim is £2,500 or less. It can be used for earlier tax years within the four-year window. For larger expense claims, or for reliefs that do not fit the P87, you may need to file a self assessment return or write to HMRC with the details.
If you already filed a self assessment return for 2022/23, the normal amendment window for that return has closed. That does not necessarily mean the money is lost. You may be able to make an overpayment relief claim in writing, explaining the year, the reason for the overpayment and the evidence you hold.
Keep copies of everything you send. If you claim online, save the submission confirmation. If you write by post, use a tracked service and keep a copy of the letter.
If you already filed a self assessment return
A filed return can feel final, but overpayment relief exists precisely for cases where too much tax was paid and the usual correction period has passed. The claim still needs to be made before the four-year deadline. It is not a free pass to reopen every old return; you need to identify a genuine overpayment and explain why it happened.
Where the overpayment arises from an error in your return, take advice if the amount is significant or the facts are complicated. For straightforward cases, a clear letter with supporting documents is often enough.
Records, scams and the deadline
Keep your evidence for at least the period HMRC may check. In practice, that means retaining documents for several years after the claim. Do not rely on an old employer or pension provider to hold records indefinitely.
Be alert to scams. HMRC will not cold-call you demanding bank details for a refund, nor will it ask you to pay a fee to release one. Use the official government website and your personal tax account.
The practical message is simple: if you think you overpaid tax in 2022/23, review the position now rather than in the spring of 2027. The deadline of 5 April 2027 is fixed. A short checklist today could recover money you had forgotten you were owed.
