Unpaid Crypto Tax From Earlier Years: HMRC's Disclosure

Updated 17 October 2026

General information only, not tax advice. We are not HMRC and are not affiliated with it. Check GOV.UK. Sources read October 17, 2026. Anything marked expected should be re-checked (re-check planned December 1, 2026). Examples use GOV.UK's own figures or made-up figures. Do not enter personal identifiers (National Insurance number, UTR, name, date of birth) on this site. This page contains no affiliate links.

Short answer: GOV.UK's page Tell HMRC about unpaid tax on cryptoassets (last updated January 15, 2024) describes a voluntary disclosure for unpaid income tax or CGT on exchange tokens, NFTs and utility tokens. Income or gains for the current or previous tax year go on your Self Assessment return instead. The page says that if you don't declare unpaid tax you could face additional interest and penalties.

What you need before you start

You sign in to submit. HMRC lists: personal details; the number of cryptoasset transactions; the proceeds or income not declared (before costs) and the years involved; acquisition costs and expenses; gains or profit with calculations; the exchanges used; the number of cryptoassets disposed of; the tax and interest owed with calculations; and whether you used a commercial crypto calculator (and which).

How many years?

Why the tax wasn't paid Years to disclose (HMRC)
You took reasonable care 4 years (current and later years reported on returns; last year on the return; the form covers the 3 years before)
You did not take care maximum 6 years (the form covers the 5 years before)
Deliberate maximum 20 years
"Deliberately" means you knew you owed tax and chose not to tell HMRC, or knew the figures on a return were wrong.

Interest and penalties

  • Interest runs daily from the date tax was due until paid; if the interest is wrong, HMRC will reject the disclosure. HMRC points to its penalties and interest calculator.
  • You work out the penalty using HMRC's factsheet on penalties for inaccuracies and for failure to notify, and give an explanation on the form. If HMRC thinks your penalty is too low, it may carry out a further check.

After you submit

HMRC writes with a payment reference (if none within 15 working days, contact the helpline). You should pay within 30 days of submitting; if you can't, contact HMRC. HMRC then accepts the offer or says it can't. If it finds you knowingly gave incorrect information, higher penalties are possible.

Practical steps (educational)

Reconstruct your records (reconcile your records); value in pounds (valuation); compute gains by pools (pooling mistakes). A tax adviser can help; HMRC allows you to appoint one (temporary authorisation is required for an agent to submit).

FAQ

Does CARF make this more relevant? Platform reports begin in 2027 ([what HMRC will receive](../what-hmrc-will-receive-from-crypto-platforms-for-2026/)); the disclosure page doesn't link the two.

Is a disclosure the same as an enquiry? Not covered by the page read.

What we could not verify

Uncertain. These points were not confirmed on the pages read. A re-check of the GOV.UK pages is planned for 1 December 2026.

  • Penalty percentages for inaccuracy or failure to notify: the factsheet was not read.
  • The interest rate and the penalties and interest calculator: not read.
  • Whether disclosure terms changed after the January 2024 update: no later update shown on the page.
  • Whether the number-of-years rules interact with CARF data HMRC will hold from 2027: unverified.
  • This guide is not a recommendation to disclose; individual circumstances need professional advice.

Sources (official)

The CARF Readiness Checker runs in your browser. It does not store what you enter and it does not ask for personal identifiers.