# January Self Assessment deadline — crypto tax checklist

Online Self Assessment and payment for 2025/26 are due 31 January 2027. Crypto disposals go on SA108. Late filing starts at £100 fixed penalty. Gather exchange CSVs, apply UK pooling rules, pay any tax due by midnight 31 January, and keep records five years.

## Key facts
- 31 January 2027: file and pay for tax year 2025/26 (ended 5 April 2026).
- Register by 5 October 2026 if you first owed tax in 2025/26.
- SA108 crypto boxes mandatory for relevant disposals from 2024/25 returns onward.
- Payment on account may apply — 31 July 2026 and 31 January 2027 instalments.
- Late filing penalty: £100 immediately, more after 3 and 6 months.
- Late payment interest accrues from 1 February — pay what you can if short.

## Do crypto holders need to file?

File if crypto gains exceed the annual exempt amount after losses, if proceeds exceed £50,000 in the year, if you have crypto income (staking, mining, employment), or if HMRC wrote to you. Even with losses, filing preserves loss carry-forward.
## Eight-week checklist

Week 8: export all exchange CSVs. Week 6: import to tax software or spreadsheet with UK pooling. Week 4: reconcile DeFi and wallet transfers. Week 3: complete SA108 draft. Week 2: submit return, note payment reference. Week 1: pay by bank transfer or debit card — allow 3 working days for BACS.
## SA108 crypto section

Declare number of disposals, total proceeds, gains and losses in the cryptoasset section. Do not net losses against gains incorrectly across asset classes — follow form instructions. Our SA108 guide maps each box.
## Payment on account

If your last Self Assessment bill was over £1,000, HMRC may require payments on account (50% each in January and July). Crypto volatility does not reduce POA — request reduction via SA303 if next year's bill will be lower.
## If you cannot pay in full

File on time even if you cannot pay — penalties are worse for late filing than late payment. Contact HMRC for Time to Pay arrangement. Do not ignore letters.
## After filing

Save PDF confirmation, software report, and source CSVs until at least five years after the deadline. CARF data from exchanges may arrive after you file — keep evidence if HMRC enquires.

## FAQs
### Can I file early?

Yes — online filing opens after the tax year ends. Early filing helps avoid January rush.
### What if I made no gains?

You may still need to file if proceeds exceeded £50,000 or HMRC requires a return.

## Sources

- [HMRC — Self Assessment deadlines](https://www.gov.uk/self-assessment-tax-returns)
- [HMRC — Late filing penalties](https://www.gov.uk/self-assessment-tax-returns/penalties)

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— Digital Assets UK (https://digital-assets.co.uk/tax/january-self-assessment-deadline-crypto/), reviewed 2026-06-23. Source: https://www.gov.uk/self-assessment-tax-returns