CryptoTax UK · Guide
UK crypto tax deadlines — every date you need to know
Missing an HMRC deadline triggers automatic penalties — even if you owe no tax. This page sets out the key dates for the 2024/25 and 2025/26 tax years, and what happens if you miss them. Educational only — not tax advice.
Calculate what I owe before the deadline →Key dates for the 2024/25 tax year
5 October 2025: deadline to register for Self Assessment. 31 October 2025: deadline for paper Self Assessment filing. 31 January 2026: deadline for online Self Assessment filing AND payment of tax owed for 2024/25. 31 July 2026: second payment on account (if applicable).
Key dates for the 2025/26 tax year
5 October 2026: register for Self Assessment. 31 October 2026: paper filing deadline. 31 January 2027: online filing deadline and tax payment. 31 July 2027: second payment on account. The pattern repeats each year — the online filing deadline is always 31 January following the end of the tax year.
Payment on account
If your tax bill exceeds £1,000 and less than 80% is collected through PAYE, HMRC requires advance payments on account for the following year. These are typically 50% of last year's tax bill, due on 31 January and 31 July. If your crypto gains vary significantly year to year, you may need to reduce your payments on account — done via Self Assessment.
What happens if you miss the deadline
Immediate £100 penalty on 1 February. Daily £10 penalties from 3 months late (up to £900 over 90 days). Further £300 or 5% of tax at 6 months. Another £300 or 5% of tax at 12 months. Plus interest on unpaid tax from 1 February. Penalties accumulate regardless of whether you owe any tax.
Frequently asked questions
What if I realised I need to file after the deadline?
File as soon as possible — penalties increase the longer you wait, but filing promptly typically limits the damage. If there is a reasonable excuse (serious illness, bereavement, HMRC online service failure), you may be able to appeal the initial penalty.
Do I need to register for Self Assessment every year?
No — once registered, you stay in Self Assessment. You must notify HMRC if you no longer need to file (e.g. no taxable income or gains). If you stop having taxable crypto gains, you can ask HMRC to take you out of Self Assessment.
Can I get an extension on the 31 January deadline?
There is no automatic extension to the UK Self Assessment deadline. In exceptional circumstances (e.g. a significant technical failure of HMRC's own service), HMRC may waive penalties — but this is rare and not something to plan for.
When do I need to pay if I owe crypto CGT?
Capital Gains Tax owed is due by 31 January following the end of the tax year. For 2024/25 gains, the payment deadline is 31 January 2026. If you cannot pay, contact HMRC about a Time to Pay arrangement as early as possible.
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Calculate what I owe before the deadline →Educational guidance only. CryptoTax UK is not a regulated tax adviser and the information above does not constitute tax, legal or financial advice. Always confirm your specific position with HMRC or a qualified accountant before filing.