Most UK tax claims and elections must be made within four years of the end of the tax year or company accounting period they relate to. Many of the reliefs people use most often have their own shorter deadlines, commonly one or two years, written into the specific legislation, and once a deadline passes the relief is usually lost for good.

What is the general time limit for making a tax claim?

For income tax and capital gains tax, section 43(1) of the Taxes Management Act 1970 (TMA 1970) says that, subject to any provision prescribing a longer or shorter period, no claim for relief may be made more than four years after the end of the tax year to which it relates. Corporation tax has a matching rule in paragraph 55 of Schedule 18 to the Finance Act 1998: a claim for relief must be made within four years from the end of the accounting period to which it relates. The four year period in both provisions was substituted by the Finance Act 2008 with effect from 1 April 2010; before then the general limit was longer.

The words “subject to any provision prescribing a longer or shorter period” are the important part. The four year rule is only the fallback. If the section that creates a relief sets its own deadline, that deadline wins, and it is very often shorter.

Illustration only. A claim governed by the general rule for the tax year 2022 to 2023, which ended on 5 April 2023, must be made by 5 April 2027. A company claim for an accounting period ending 31 December 2022 must be made by 31 December 2026.

Which common claims and elections have shorter deadlines?

The table below lists frequently used reliefs where the statute sets its own limit. Each deadline is taken from the section named.

Claim or election Deadline Legislation
Amending a self assessment return 12 months after the filing date TMA 1970 s9ZA
Amending a company tax return 12 months after the filing date FA 1998 Sch 18 para 15
Trade loss relief against general income (individuals) First anniversary of the normal self assessment filing date for the loss making year ITA 2007 s64(5)
Company trade loss against total profits, including carry back Two years after the end of the loss making period, or a further period allowed by an HMRC officer CTA 2010 s37(7)
Business asset disposal relief First anniversary of the 31 January following the tax year of the disposal TCGA 1992 s169M(3)
Main residence nomination where there are two or more residences Within two years from the beginning of the period TCGA 1992 s222(5)
Short life asset election Income tax: the normal time limit for amending the return; corporation tax: two years after the end of the chargeable period CAA 2001 s85(2)
Averaging for farmers and creators First anniversary of the normal self assessment filing date for the last year in the claim ITTOIA 2005 s222(5) and s222A(6)

Negligible value claims work slightly differently. Under section 24(2) of the Taxation of Chargeable Gains Act 1992 (TCGA 1992), the claim can deem the loss to arise at an earlier time, but for capital gains tax that earlier time cannot be more than two years before the beginning of the tax year in which the claim is made. See negligible value claims for how that backdating works in practice.

Are there claims with a longer deadline than four years?

Yes, though they are fewer. A claim for Enterprise Investment Scheme income tax relief can be made up to the fifth anniversary of the normal self assessment filing date for the tax year in which the shares were issued (Income Tax Act 2007, s202). The Enterprise Investment Scheme page covers the other conditions.

There is also a safety valve where HMRC raises an assessment late. Under TMA 1970 s43(2), a claim that could not have been allowed but for an assessment made after the end of the tax year may be made at any time before the end of the tax year following the one in which the assessment was made. That gives a taxpayer a chance to claim reliefs that only become relevant because of HMRC’s late assessment, even if the ordinary deadline has passed.

What does “the normal self assessment filing date” mean when counting?

Many income tax deadlines are expressed as the first anniversary of the normal self assessment filing date. Under TMA 1970 s9ZA(3), the filing date for a return for one tax year is 31 January in the following tax year, or three months after the notice to file if HMRC issued the notice after 31 October. The first anniversary of that date is therefore a further 12 months on.

Illustration only. A sole trader makes a trading loss in 2024 to 2025. The normal filing date for that year is 31 January 2026, so a claim to set the loss against general income must be made by 31 January 2027. If the same person disposed of a qualifying business in 2024 to 2025, the business asset disposal relief claim has the same 31 January 2027 deadline.

Counting from the wrong starting point is one of the most common errors. Four years from the end of the tax year, twelve months from the filing date and two years from the end of an accounting period all produce different dates for the same underlying year.

Can a claim still be made after the return can no longer be amended?

Often, yes. TMA 1970 s42(2) requires a claim to be included in a return if it could be made that way. Once the 12 month amendment window under s9ZA has closed, a claim that still has time left under its own rule can be made separately, in writing. That is how most claims with a four year limit are made in practice when an error is spotted late.

Overpaid tax is a good example. A claim for overpayment relief under Schedule 1AB to TMA 1970 may not be made more than four years after the end of the relevant tax year. Where the amendment window is still open, amending the tax return is usually simpler. VAT has its own separate four year cap on claims, explained on the VAT four year cap page.

Capital losses are also caught by the general rule. Under TCGA 1992 s16(2A), a loss is not an allowable loss unless the person gives HMRC notice quantifying it, and TMA 1970 sections 42 and 43 apply to that notice as if it were a claim. An unreported loss on shares sold several years ago can therefore still be claimed only if it is within four years of the end of the tax year of the disposal.

How do these limits compare with HMRC’s own time limits?

The rules are not symmetrical. HMRC’s ordinary limit for an income tax or capital gains tax assessment is four years after the end of the tax year (TMA 1970 s34), extended to six years where the loss of tax was brought about carelessly and to 20 years for deliberate behaviour or failure to notify chargeability (TMA 1970 s36). A taxpayer’s claims, by contrast, do not get longer simply because the error was HMRC’s or because an earlier year is reopened, apart from the s43(2) safety valve above. The page on how far back HMRC can go covers assessments in more detail.

What mistakes cause reliefs to be lost?

  • Assuming four years applies to everything. Loss relief against general income, business asset disposal relief and short life asset elections all have shorter limits.
  • Relying on HMRC discretion. Only some provisions allow HMRC to accept a late claim. CTA 2010 s37(7) expressly lets an officer allow a further period for company loss claims; most income tax provisions contain no such power.
  • Making a vague claim. TMA 1970 s42(1A) requires a claim for a relief, allowance or repayment to be for an amount quantified at the time the claim is made. A letter saying “we intend to claim” does not stop the clock.
  • Forgetting that elections can be irrevocable. A short life asset election cannot be withdrawn once made (CAA 2001 s85(4)), so a late decision cannot be fixed by making and then reversing it.
  • Not diarising consequential claims. When profits change after an enquiry, check whether averaging, loss or capital allowance claims for linked years need revisiting before their own deadlines pass.

How should an adviser keep track of deadlines?

Record each relief and election against the specific section that governs it, the start date for counting and the resulting calendar date, rather than a generic “four years” note. Review the list at each year end and whenever a return is amended or an enquiry closes, because a change to profits can open a claim that did not exist before. Where a deadline is close, submit a quantified claim with the best figures available and correct it later within the time limit, rather than waiting for perfect numbers.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.