No. 20 · Returns & deadlines · the forms
Where losses go on your Self Assessment return
A 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.
On this page
- Capital losses go in the "losses in the year" box for each type of asset on the capital gains pages, with brought-forward and carried-forward losses in a separate section.
- Self-employment and partnership pages each have boxes for loss brought forward, loss against other income, loss carried back and loss carried forward.
- The UK property pages have boxes for loss brought forward used, the year’s loss, loss against total income ("unusual") and loss carried forward.
- The 2026/27 forms haven’t been published yet — box numbers can change, so always check the notes for the year you’re filing.
Capital gains summary (SA108)
HMRC’s notes say you fill in these pages if, among other things, you sold chargeable assets worth more than £50,000, your gains before losses were more than the annual exempt amount, or you want to claim an allowable capital loss. Don’t deduct the annual exempt amount yourself — HMRC applies it.
In the 2025–26 edition:
| What | Box(es) |
|---|---|
| Losses in the year — residential property; cryptoassets; other property and assets; listed shares; unlisted shares | 7; 13.5; 19; 27; 35 |
| Claim or election codes (e.g. NVC for a negligible value claim) | 8; 13.6; 20; 28; 36 |
| Total gains or losses already reported on UK property 60-day returns | 9 |
| Share losses set against income: this year / last year (and the EIS/SEIS part) | 41–44 |
| Losses brought forward and used this year | 45 |
| Trading losses of this year set against gains | 46 |
| Losses available to carry forward | 47 |
| Losses used against an earlier year’s gain (e.g. year of death) | 48 |
| Adjustments (e.g. clogged losses, re-allocating losses) | 51 |
| Any other information (computations, negligible value claim details) | 54 |
See how to claim a capital loss and negligible value claims.
Self-employment (SA103S short / SA103F full)
| What | SA103S | SA103F |
|---|---|---|
| Loss brought forward set off against this year’s profits | 29 | 74 (and 73.4 against spread transition profit) |
| Net loss / adjusted loss for the year | 32 | 77 |
| Loss set off against other income of the same year | 33 | 78 |
| Loss carried back to previous years (details in "Any other information") | 34 | 79 |
| Total loss to carry forward (including unused losses brought forward) | 35 | 80 |
The notes repeat the cap: relief against total income each year is limited to the greater of £50,000 or 25% of adjusted total income. If you use the trading allowance you can’t create a loss — deduct your actual expenses instead if you want loss relief. See sideways relief and carry forward.
Partnership (SA104S / SA104F)
Your share of a partnership loss has similar boxes: losses brought forward used (17), adjusted loss (21), loss against other income (22), loss carried back (23) and loss to carry forward (24). The full pages also have partnership UK property boxes, including loss against total income (39) and loss to carry forward (40). See partnership losses.
UK property (SA105)
| What | Box |
|---|---|
| Loss brought forward used against this year’s profits | 39 |
| Adjusted loss for the year | 41 |
| Loss set off against total income — the form says "this will be unusual" | 42 |
| Loss to carry forward, including unused losses brought forward | 43 |
| Residential finance costs (a tax reduction, not a loss) | 44, 45 |
Former furnished holiday lettings boxes (5 to 19) are no longer used from 2025–26. See rental property losses.
Additional information (SA101)
The 2025–26 additional information pages include boxes under "Other information" for relief now for 2026–27 trade losses or certain capital losses carried back to an earlier year (boxes 3 to 5). HMRC’s notes explain the claim is for the later year but the relief is worked out using the earlier year’s income. "Other tax reliefs" includes post-cessation trade relief and pre-incorporation losses.
Making Tax Digital
If you use Making Tax Digital for Income Tax, HMRC’s helpsheet HS227 says you make claims and adjustments through your software rather than these boxes — see Making Tax Digital.
Sources
Checked 4 October 2026 for the 2026/27 tax year. We read these primary sources for this guide:
- HMRC: Self Assessment Capital Gains Tax summary (SA108) and notes (gov.uk)
- HMRC: Self-employment (short) SA103S and notes (gov.uk)
- HMRC: Self-employment (full) SA103F and notes (gov.uk)
- HMRC: Partnership (short) SA104S and notes (gov.uk)
- HMRC: Partnership (full) SA104F and notes (gov.uk)
- HMRC: UK property SA105 and notes (gov.uk)
- HMRC: Additional information SA101 and notes (gov.uk)
- HMRC helpsheet HS227: Relief for trading losses (2026) (gov.uk)
- HMRC helpsheet HS204: Limit on Income Tax reliefs (2026) (gov.uk)
Contains public sector information licensed under the Open Government Licence v3.0. This guide adapts and summarises that information in our own words. taxloss.co.uk is an independent guide. It is not affiliated with, endorsed by or connected to HM Revenue & Customs (HMRC) or the UK Government. Spotted something out of date? Tell us.