Four years of unclaimed CIS refunds: the 5 April 2027 cut-off for 2022/23

By Patrick Roper ACA, ICAEW chartered accountant. Last reviewed 1 November 2026. Figures next checked by 6 April 2027.

You can go back four years. HMRC's rule for overpaid tax is that a claim must be made within four years of the end of the tax year it relates to, so on 1 November 2026 the years 2022/23, 2023/24, 2024/25 and 2025/26 are open. The 2022/23 year closes on 5 April 2027 and cannot be reopened after that. A subcontractor on 20% deductions who never filed is usually owed money for each of those years.

Which years are open today

The refund firms say "up to four years" without dates. The dates come from HMRC's overpayment relief rule: four years after the end of the tax year. Tax years end on 5 April.

Why old years are usually worth more

Someone who never filed has never had the personal allowance or any expenses set against the 20% taken at source. The whole of the allowance, £12,570 in each recent year, has been taxed at 20% when it should not have been taxed at all. That alone is £2,514 a year before a single expense is counted. Four open years at that rate is where the larger refunds come from, and it is also why the firms advertise the four-year figure so hard.

What a late claim involves

1. Find out whether HMRC asked you to file. Check for notices to file or penalty letters. If a return was requested and not sent, late-filing penalties exist and HMRC will set them against the refund; the refund is usually larger than the penalties, but you should know the number first.
2. Rebuild each year. Gross pay and deductions from the statements, or from bank statements plus the figures HMRC holds. Expenses from bank records, with receipts where they survive.
3. File a return for each year, oldest first, because 2022/23 is the one with the deadline. Each year is a separate return and a separate refund.
4. Register for Self Assessment if you never did. A Unique Taxpayer Reference is needed before anything can be filed, and HMRC can take a few weeks to issue one, which is a reason not to leave 2022/23 until March 2027.

The 5 April 2027 line

After 5 April 2027 the 2022/23 year is closed. There is no extension for not knowing, and no refund firm or accountant can reopen it. If you worked under CIS in that year and never filed, that year needs to be in before then, with the Unique Taxpayer Reference, the figures and the evidence all in place first. Starting in the new year is leaving it late.

Fees for back years

We file up to four earlier years together with this year's return for £399, paid when you approve them, with one summary across the years. The single-year fee is £249, or £149 if that year shows no refund is due. HMRC's own service is free for every year, and the four-year rule is the same whoever files.