Self Assessment Tax Return for Crypto: UK Guide for 2025/26 Filing

UK TAX
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A stylised digital illustration of a UK HM Revenue & Customs (HMRC) self-assessment tax return form. The document is labeled 'SELF ASSESSMENT TAX RETURN SA108 CAPITAL GAINS 2024-2025' in bold black text. The HMRC logo, appears in green at the top left. The paper has a folded corner, and the background is a deep shade, creating a sense of mystery.
Samantha Adams
Written by
Head of Content at Recap

Filing your Self Assessment tax return for the 2025/26 tax year? HMRC's Self Assessment form now includes a dedicated section for cryptoassets — first introduced for 2024/25 and continuing for 2025/26. If you're a UK crypto investor, here's how to report your gains correctly for the 2025/26 return, due online by 31 January 2027.

What’s changing on the Self Assessment Tax Return?

Until 2023/24, if you sold, swapped, or spent crypto, you reported any gains in the general Capital Gains section of the Self Assessment form alongside stocks and shares. From the 2024/25 tax year onward, there's a separate section specifically for cryptoasset disposals — and that dedicated section continues to apply for the 2025/26 return you'll file by 31 January 2027.

This means:

  • More visibility for HMRC into crypto activity
  • A clearer structure for reporting crypto gains and losses

How to report crypto capital gains in HMRC’s new self assessment form

Flat lay image of the updated HMRC Self Assessment tax return form with a pen and notebook, illustrating crypto investors preparing to file their tax return.

The crypto capital gains section of HMRC's Self Assessment Tax Return is pictured above. Here's what HMRC are asking you to declare on your 2025/26 return:

  • Total number of disposals
  • Disposals proceeds
  • Allowable costs
  • Gains in the year (before losses)
  • Losses in the year

You’ll also need to include calculations and supporting evidence to show that you have followed HMRC’s pooling rules and demonstrate your proceeds and allowable costs. The Recap report which includes disposals and acquisitions does this sufficiently.

There is no change to reporting taxable income from crypto. You can check out our detailed article on how to file your crypto taxes for more information.

What about the 2024/25 split tax year?

The 2024/25 tax year was a "split" year — HMRC introduced new CGT rates (18% basic / 24% higher) partway through, on 30 October 2024. Capital gains made in 2024/25 may therefore be taxed at different rates depending on when they were realised. For 2025/26, the new 18%/24% rates apply to the whole year, so no split is needed.

If you're filing or amending a 2024/25 return, the Self Assessment form includes prompts for the dual-rate split, but it's crucial that your records distinguish between disposals before and after 30 October 2024.

An example of the capital gains summary of a Recap report for the 2024/25 tax year, including total gains before and after the new tax rates on 30th October.

Recap makes this easy - your dashboard shows realised gains split across the two periods, with tax estimated accordingly. HMRC's Adjustment Calculator can also help you work out the adjustment for your Self Assessment tax return for disposals of assets on or after 30 October 2024 where the rates changed.

Recap screenshot showing an example of the capital gains calculation for the split tax year.

When do I need to file my 2025/26 tax return?

You don't need to file your 2025/26 return until 31 January 2027, but the filing window opens on 6 April 2026 — so you can get it done early. That said, waiting until at least May is advised because the bed-and-breakfast rule looks 30 days into the next tax year.

Can Recap help?

Recap helps you track and calculate your crypto taxes throughout the year, so you’re not scrambling for data when the deadline hits. Log in to Recap and get your data ready early for a stress-free tax season.

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