January Self Assessment deadline — crypto tax checklist
Quick answer: 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.
The 31 January deadline catches thousands of crypto holders each year. This landing page is your checklist for filing on time — whether your tax year is 2025/26 (deadline 31 January 2027) or you are planning ahead for 2026/27 (deadline 31 January 2028).
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.
Frequently asked questions
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.