Capital Gains Tax on Your 2025/26 Tax Return: Dates, Rates and the SA108 Boxes
The return you file this winter covers gains made between 6 April 2025 and 5 April 2026. If you are in Self Assessment, they go on the capital gains pages (SA108) of your 2025/26 return, filed online by 31 January 2027, with the tax paid the same day.27 If you are not, a UK resident can use HMRC's real-time service instead: report by 31 December 2026 and pay by 31 January 2027.1 The rates were 18% and 24% all year, after a £3,000 allowance; Business Asset Disposal Relief was 14%.3
| Real-time CGT service, 2025/26 gains (not in Self Assessment) | Report by 31 December 2026 |
| Self Assessment return and CGT payment, 2025/26 | 31 January 2027 |
| Amend your 2024/25 return (for example, a missed gain or loss) | 31 January 2027 |
| Claim a 2022/23 capital loss | 5 April 2027 |
| Claim Business Asset Disposal Relief on a 2025/26 sale | 31 January 2028 |
- Fill in the capital gains pages if you sold chargeable assets worth more than £50,000, your gains before losses were more than £3,000, or you want to claim a loss.2
- 2025/26 rates: 18% within your unused basic-rate band, 24% above it, for the whole year. BADR and Investors' Relief: 14% (18% from 6 April 2026).3
- A property sale already reported on a 60-day UK property return still goes on the tax return: boxes 9 and 10, with the reference in box 54.2
- CGT is paid with the January balancing payment and is left out of payments on account.613
- GOV.UK: the current penalties apply to the 2025/26 return due 31 January 2027.8
Which gains go on the 2025/26 return?
Disposals between 6 April 2025 and 5 April 2026. For most sales the date of disposal is the date the contract is made (exchange, for property), not completion, so a house that exchanged on 28 March 2026 and completed in April 2026 belongs on the 2025/26 return.
You do not need the capital gains pages if all you sold were private cars, personal possessions worth up to £6,000 each, shares in an ISA, gilts or Premium Bonds, or your main home fully covered by Private Residence Relief.2
2025/26 vs 2026/27: what was different?
| Item | 2025/26 | 2026/27 |
|---|---|---|
| Annual exempt amount (most trustees) | £3,000 (£1,500) | £3,000 (£1,500) |
| Rates for individuals | 18% and 24% | 18% and 24% |
| Business Asset Disposal Relief or Investors' Relief | 14% | 18% |
| Trustees | 24% | 24% |
| Basic rate band (for the 18%/24% split) | £37,700 | £37,700 |
Source: HMRC's Capital Gains Tax and Income Tax rate tables, checked 22 October 2026.34 The rates changed part-way through 2024/25 (on 30 October 2024), not during 2025/26, so a 2025/26 return has one set of rates.
Worked example: a share sale in December 2025
Asha earned a £40,000 salary in 2025/26 and has no other income. In December 2025 she sold shares held outside an ISA for £62,000; her Section 104 pool cost for them was £40,000, including dealing costs. Because the proceeds are over £50,000 she must complete the capital gains pages whatever the tax.2
| Gain (£62,000 − £40,000) | £22,000 |
| Less annual exempt amount | −£3,000 |
| Taxable gain | £19,000 |
| Unused basic-rate band: £37,700 − (£40,000 − £12,570) | £10,270 |
| 18% × £10,270 | £1,848.60 |
| 24% × £8,730 | £2,095.20 |
| CGT due by 31 January 2027 | £3,943.80 |
Asha's figures go in the listed shares section (proceeds £62,000, costs £40,000, gain £22,000), and she attaches her computation.2 If she is not otherwise in Self Assessment she can report through the real-time service by 31 December 2026 instead.1
Where things go on the SA108
| What you sold or claimed | Section / boxes |
|---|---|
| UK or overseas residential property, carried interest | Boxes 3 to 13C; a sale already on a UK property return goes in box 9, its tax in box 10 |
| Cryptoassets | Boxes 13.1 to 13.8 |
| Other property, assets and gains | Boxes 14 to 22 |
| Listed shares and securities | Boxes 23 to 30; real-time service gains in box 29, tax already paid in box 30 |
| Unlisted shares (including AIM) | Boxes 31 to 44 |
| Losses brought forward, BADR and Investors' Relief | Boxes 45 to 52 |
| UK property return and real-time references, elections | Box 54 |
From HMRC's SA108 notes for 2025/26 (the 2026 edition).2 Losses brought forward are used only to bring this year's gains down to the £3,000 annual exempt amount, so the rest carries on to later years.2
Selling a business in 2025/26: BADR at 14%
A qualifying business disposal made before 6 April 2026 is taxed at 14% under Business Asset Disposal Relief; from 6 April 2026 the rate is 18%.3 On a qualifying gain of £200,000, after the £3,000 allowance, that is £27,580 at 14% (it would be £35,460 at 18%). You claim it on your return or with the BADR helpsheet, and for a 2025/26 sale the claim deadline is 31 January 2028.5
Losses, mistakes and old years
- Claim a loss within 4 years of the end of the tax year it was made: a 2025/26 loss by 5 April 2030, and a 2022/23 loss by 5 April 2027.11 See how to claim a capital loss.
- Amend last year's return by 31 January 2027 if your 2024/25 return missed a gain, a cost or a loss.10
- A 60-day property payment is credited against the CGT on your return; if your final figure is lower, the difference is repaid.12
Penalties and interest
HMRC says the current penalties apply to the 2025/26 return due 31 January 2027.8 Filing late costs £100 at once, and unpaid tax picks up 5% penalties at 30 days, six months and twelve months. Interest on late tax is 7.75% a year (Bank of England base rate plus 4%) from 9 January 2026.9 For the full timetable, see CGT reporting deadlines, and for the two reporting routes, Self Assessment or the real-time service.
Check the figure before you file
The calculator uses the 18%/24% split and £3,000 allowance that applied in both 2025/26 and 2026/27. For shares, the Section 104 pool calculator applies the matching rules.
Open the CGT calculatorFrequently asked questions
When is the deadline to report capital gains for 2025/26?
If you file Self Assessment, put the gains on your 2025/26 return and file online by 31 January 2027, paying the tax by the same date. If you are UK resident and not in Self Assessment, you can use HMRC's real-time Capital Gains Tax service instead: report by 31 December 2026 and pay by 31 January 2027. A UK home with tax to pay had its own 60-day deadline.
What were the CGT rates for 2025/26?
18% on gains that fit within your unused basic-rate band and 24% above it, for the whole of 2025/26, after the £3,000 annual exempt amount. Business Asset Disposal Relief and Investors' Relief were 14%; they rose to 18% from 6 April 2026.
Do I need to fill in the capital gains pages if I owe no CGT?
Yes, if you sold chargeable assets worth more than £50,000 in 2025/26, or you want to claim a capital loss. HMRC's 2025/26 notes also ask you to fill them in if your gains before losses were more than £3,000.
I already reported a property sale within 60 days. Does it go on my tax return?
Yes, if you file Self Assessment. Put the overall gain or loss in box 9 of the capital gains summary, the tax you were charged on the UK property return in box 10, and the return reference in box 54. HMRC then credits the tax you paid.
I used the real-time service for 2025/26. Do I also put it on my return?
Yes, if you are registered for Self Assessment. Each section of the capital gains pages has a box for gains already reported through the real-time service and a box for the tax already paid (for listed shares, boxes 29 and 30), and the references go in box 54.
Is CGT included in my payments on account?
No. GOV.UK says the January balancing payment includes anything you owe for capital gains, and HMRC's manual says Capital Gains Tax is excluded when payments on account are worked out. A gain on your 2025/26 return is paid by 31 January 2027 and does not increase your 2026/27 payments on account.
This page is general information, not tax advice. It reflects GOV.UK guidance and HMRC's 2025/26 Capital Gains summary notes as checked on 22 October 2026.
Sources & references
The rates, allowances and rules in this guide are drawn from the official HMRC and GOV.UK sources below, checked for the 2026/27 tax year. Each link opens the relevant government page in a new tab.
- Report and pay CGT: if you have other capital gains to report www.gov.uk/report-and-pay-your-capital-gains-tax/if-you-have-other-capital-gains-to-report
- Self Assessment: Capital Gains summary (SA108) and notes www.gov.uk/government/publications/self-assessment-capital-gains-summary-sa108
- Capital Gains Tax rates and annual tax-free allowances (all years) www.gov.uk/government/publications/rates-and-allowances-capital-gains-tax/capital-gains-tax-rates-and-annual-tax-free-allowances
- Income Tax rates and allowances for current and past years www.gov.uk/government/publications/rates-and-allowances-income-tax/income-tax-rates-and-allowances-current-and-past
- Business Asset Disposal Relief: how to claim www.gov.uk/business-asset-disposal-relief/how-to-claim
- Understand your Self Assessment tax bill: payments on account www.gov.uk/understand-self-assessment-bill/payments-on-account
- Self Assessment tax returns: deadlines www.gov.uk/self-assessment-tax-returns/deadlines
- Penalties for Making Tax Digital for Income Tax www.gov.uk/guidance/penalties-for-making-tax-digital-for-income-tax
- HMRC interest rates for late and early payments www.gov.uk/government/publications/rates-and-allowances-hmrc-interest-rates-for-late-and-early-payments/rates-and-allowances-hmrc-interest-rates
- Self Assessment tax returns: corrections www.gov.uk/self-assessment-tax-returns/corrections
- Capital Gains Tax: losses www.gov.uk/capital-gains-tax/losses
- Report and pay CGT: if you sold a UK property on or after 6 April 2020 www.gov.uk/report-and-pay-your-capital-gains-tax/if-you-sold-a-property-in-the-uk-on-or-after-6-april-2020
- HMRC Self Assessment Legal Framework SALF303: payments on account www.gov.uk/hmrc-internal-manuals/self-assessment-legal-framework/salf303