The index · 2026/27
Guides to UK tax losses
Each guide is written from GOV.UK guidance, HMRC’s internal manuals and the legislation, lists its sources, and shows when it was last checked.
A/C 01 Capital gains losses
Shares, funds, crypto, property and possessions sold or given away for less than they cost.
- 01Capital losses: what counts as an allowable losschecked 4 Oct 2026When you sell or give away an asset for less than it cost you, you may have a capital loss. It only reduces your tax once it is an "allowable loss" — which depends on the asset and on telling HMRC in time.
- 02How to claim a capital loss — and the 4-year time limitchecked 4 Oct 2026A capital loss only counts once you have told HMRC about it, with the amount. Here’s how to do that on your tax return or by letter, and the deadline you must meet.
- 03How capital losses are set against gains — and the annual exempt amountchecked 4 Oct 2026This year’s losses are used up in full first, even if that wastes your tax-free allowance. Losses brought forward from earlier years are only used to bring your gains down to the annual exempt amount — the rest carries on.
- 04Losses on disposals to family and connected peoplechecked 4 Oct 2026Sell or give something to a relative, business partner or a company you control and make a loss, and that loss is "clogged" — you can only use it against gains on other disposals to the same person. Transfers to a spouse or civil partner usually give no loss at all.
- 05Shares that have become worthless: negligible value claimschecked 4 Oct 2026If shares (or other assets) you still own have become worth next to nothing, a negligible value claim lets you be treated as having sold them, creating a capital loss. The claim can be backdated — within limits.
- 06Share loss relief: setting a loss on shares against incomechecked 4 Oct 2026Losses on shares you subscribed for in a qualifying unlisted trading company — including EIS and SEIS shares — can sometimes be set against your income instead of only against gains. The claim has a shorter deadline.
- 07Cryptoasset losseschecked 4 Oct 2026Selling, swapping or spending tokens for less than their cost gives a capital loss you can claim like any other. HMRC treats lost keys and theft differently — and worthless tokens need a negligible value claim on the whole pool.
- 08Losses when you sell property — and the 60-day UK property returnchecked 4 Oct 2026A loss on selling a second home, buy-to-let or land is a capital loss you claim in the usual way. UK residents normally only use the 60-day "Capital Gains Tax on UK property" service when tax is due — non-residents must report every disposal, even a loss.
A/C 02 Self-employed & partnership losses
When your trade or profession makes a loss: sideways relief, carry forward, carry back.
- 09Self-employed losses: your options at a glancechecked 4 Oct 2026If your trade, profession or vocation makes a loss, income tax law gives you several ways to use it — against other income this year or last, against capital gains, back against earlier years at the start or end of a business, or forward against future profits.
- 10Setting a trading loss against other income (sideways relief)checked 4 Oct 2026Sideways relief lets you set a trading loss against your total income — a salary, pension, savings or rental income — for the tax year of the loss, the year before, or both. Any unused part can be set against capital gains.
- 11Carrying a trading loss forwardchecked 4 Oct 2026A trading loss you don’t use in other ways can be carried forward and set against later profits of the same trade, first available profits first, for as long as the trade continues.
- 12Early years loss relief: losses in the first four yearschecked 4 Oct 2026A loss in the first four tax years of a new trade can be carried back against your total income of the three tax years before the loss, earliest year first — often giving a repayment of tax you paid as an employee.
- 13Terminal loss relief when a business stopschecked 4 Oct 2026When you permanently stop trading, the loss of your final 12 months can be carried back against profits of the same trade in the final tax year and the three tax years before it, latest year first.
- 14The cap on loss relief and other restrictionschecked 4 Oct 2026Several loss reliefs against general income are capped at £50,000 or 25% of adjusted total income, whichever is higher. Non-active traders and some partners face a separate £25,000 limit, and uncommercial trades get no sideways relief at all.
- 15Losses under the cash basischecked 4 Oct 2026From 2024/25 the cash basis is the default way for sole traders and most partnerships to work out profits — and the old restriction on cash-basis trading losses has gone. Landlords are different: property losses on the cash basis still can’t be set against other income.
- 16Partnership losseschecked 4 Oct 2026When a partnership makes a loss, each partner is treated as having a loss from their own notional trade and claims relief for their share on their own tax return. Limited and non-active partners face extra limits.
A/C 03 Rental property losses
Losses from letting UK property and how they are carried forward.
A/C 04 Company losses
Limited companies: carry forward, carry back and group relief — an overview.
A/C 05 Returns, deadlines & records
Self Assessment boxes, Making Tax Digital, amending a return, evidence and help.
- 19Deadlines for loss claimschecked 4 Oct 2026Every loss relief has a time limit, and they aren’t all the same. Some run 4 years from the end of the tax year; some only to the first anniversary of the 31 January filing date. Here are the main ones in one place, with the 2026/27 dates.
- 20Where losses go on your Self Assessment returnchecked 4 Oct 2026A plain-English map of the loss boxes on the Self Assessment supplementary pages — capital gains (SA108), self-employment (SA103), partnership (SA104), UK property (SA105) and additional information (SA101). Box numbers are from the 2025–26 forms.
- 21Amending a return or claiming laterchecked 4 Oct 2026Forgot to claim a loss? You can usually amend your Self Assessment return within 12 months of the 31 January deadline. After that, many loss claims can still be made by letter within their own time limits — and overpayment relief is available for up to 4 years.
- 22Making Tax Digital for Income Tax from April 2026checked 4 Oct 2026Since 6 April 2026, sole traders and landlords with qualifying income over £50,000 must keep digital records, send quarterly updates and file their tax return through compatible software. Here’s who is affected, when, and what GOV.UK says about losses.
- 23Records and evidence HMRC may ask forchecked 4 Oct 2026To claim a loss you need to be able to show how you worked it out. What to keep for capital losses, crypto and business losses, how long to keep it, and what HMRC can ask for in a compliance check.
- 24When to get professional helpchecked 4 Oct 2026Many losses are simple enough to claim yourself. Some aren’t — large or complex losses, businesses stopping, partnerships and companies, overseas issues or an HMRC check. Here’s who can help, and how to choose.