HMRC Crypto Letter: What It Means, What to Do

A letter, email or text from HMRC about cryptoassets is, on HMRC's own description, a prompt to check that you have declared your crypto activity correctly. It is not an assessment, a bill or an accusation. GOV.UK says that "if you have traded in cryptoassets, HMRC may contact you by letter, email or text message," and that the message links to guidance on checking and reporting your crypto income and gains. What you owe, if anything, depends on your own disposals and the tax years involved, and the route for putting an earlier year right depends on how far back it goes.

The sources here are GOV.UK pages only. Descriptions of the letters by accountancy firms and software vendors differ from one another and from HMRC's own, so they are left out. Everything below is general information about published guidance and not advice on any person's tax.

What HMRC says the contact is

The cryptoassets entry in HMRC's page on genuine contact (last updated October 21, 2026) is short. It says the letter or email will contain links to guidance on checking that you have declared your crypto activities correctly, on reporting crypto income and gains, on how crypto transactions are taxed for individuals (an HMRC video) and on when tax applies when you sell. It also explains what a disposal is. The text message "will direct you to guidance on GOV.UK." The entry gives no dates for a contact period, does not list actions to take and, unlike some other entries on the same page, does not list things HMRC will never ask for.

The same page says HMRC may write to you before following up by email, call or text, and describes that as "an extra level of security." So a letter followed by a text is a documented pattern. A text with no earlier letter, or an email that asks for a payment or personal details, is not covered by the cryptoassets entry, and the page's general advice applies: check the contact against HMRC's list of genuine contacts, use the official helplines, and report suspicious emails, texts and calls through the reporting page on GOV.UK. A practical habit follows from this. Type gov.uk addresses into the browser yourself and do not use a link in an unexpected message.

Three different pieces of paper

People use "HMRC letter about crypto" for three different things, and only some of them are described in the GOV.UK pages read for this article.

A reader whose letter asks for specific documents, quotes a tax year and a reference, or refers to a return already filed has the third kind, and the right step is HMRC's own contact route or a qualified adviser. A reader whose letter points to guidance and says to check has the first. The second only exists if you have already made a disclosure.

Which route fits which year

The GOV.UK page on selling cryptoassets (last updated October 5, 2026) gives two ways to report disposals: complete a Self Assessment return at the end of the tax year, or use the Capital Gains Tax real time service. It says the cryptoasset section on the Self Assessment return is available for the tax year 2024 to 2025 onwards, and that exchange reports of your transactions are "not tax calculations" and do not track pooled costs. For earlier years with unpaid tax, the page points to a disclosure service.

The disclosure page, "Tell HMRC about unpaid tax on cryptoassets" (published November 29, 2023, last updated January 15, 2024), draws the line more precisely: income or gains from the current or previous tax year go on your Self Assessment return rather than through the disclosure. The service covers Capital Gains Tax and Income Tax on exchange tokens such as bitcoin, NFTs and utility tokens. Tax unpaid on other matters uses a different guide.

On October 23, 2026 the current tax year is 2026 to 2027, which began on April 6, 2026. The previous year, 2025 to 2026, ended on April 5, 2026, and its Self Assessment return is not due until January 31, 2027. So in the autumn of 2026, a gain from 2025 to 2026 belongs on a return, and a gain from 2024 to 2025 or earlier that was never reported is a candidate for the disclosure route.

Three invented readers show how the split works. One sold coins during 2025 to 2026 and has not filed that year's return yet: the gain goes on the Self Assessment return, not through a disclosure. A second sold coins in 2022 to 2023, never reported them, and is now in 2026 to 2027: that is an earlier year with unpaid tax, so the disclosure page is the relevant route. A third has both, and would use the return for the recent year and the disclosure for the earlier one. The page says nothing about someone who is unsure whether a disposal happened, and for that the records question below comes first.

How far back each behaviour reaches

HMRC ties the number of years to why the tax went unpaid. Both GOV.UK pages that state it, "Tell HMRC about unpaid tax on cryptoassets" and "How to make a voluntary disclosure to HMRC," say the same thing in slightly different words. For reasonable care the disclosure page says to "fill in the disclosure form and pay us what you owe for the 3 years before this one," and the general guide says "the 3 years before this." For care not taken the crypto page tells you to disclose the 5 years before this one, and the general guide says "the 5 years prior to this." Both pages add that the current and later years must be accurately reported and that the prior year is reported on its return, and both state a maximum of 4 years in total for reasonable care, a maximum of 6 years for care not taken, and "a maximum of 20 years" for a deliberate failure.

Read together, that means the previous tax year goes on its return and the disclosure goes back a further 3 or 5 years before it. With 2026 to 2027 as the current tax year, that gives:

The year lists are this page's reading of how the pages count, applied to the tax year in progress on October 23, 2026, and not HMRC's statement of any person's position. Because the lists change with the date, and because a mistake in either direction matters, confirm the years with the helpline number on the disclosure page or with an adviser before putting figures in an offer. HMRC defines deliberate as knowing you owed tax and choosing not to tell it, or knowing your return figures were wrong when you sent it in.

What the years in scope mean in pounds

The years HMRC can reach back to are not equally expensive, because the Capital Gains Tax allowance and rates changed. HMRC's page on rates and allowances (updated April 13, 2026) gives the individual annual exempt amount as 12,300 pounds for 2021 to 2022 and 2022 to 2023, 6,000 for 2023 to 2024, and 3,000 for 2024 to 2025, 2025 to 2026 and 2026 to 2027. For assets other than residential property it gives two rates, 10 percent and 20 percent until October 29, 2024, and 18 percent and 24 percent from October 30, 2024 onwards. The page does not say which rate applies to which taxpayer. The higher of the two rates is used below, and a taxpayer whose income leaves room in the basic rate band could pay the lower one on part of a gain.

Take the same net gain, 10,000 pounds after the pooled cost has been taken off, in each of five years. The gain is the figure after the rules on this site's UK tax guide have been applied.

The same disposal of the same size could produce nothing owed in 2021 to 2022 and 1,680 pounds owed in 2025 to 2026. That is the reason to work out each year separately, from records, before concluding that a letter means a large bill. The example uses one gain per year, ignores same-day and 30-day matching, and assumes the person is not otherwise using the allowance. It also leaves out interest, which runs daily on unpaid tax, and any penalty, which depends on the behaviour. Tax owed is only one part of what a disclosure covers.

The table also gives a way to see the scale of the penalty ceilings. If the three middle rows were the only unpaid years, with 0, 800 and 1,400 pounds of tax, the total is 2,200 pounds. The general guide's ceiling of 100 percent of the tax for a UK income or gain would be 2,200 pounds of penalty at most, and the 200 percent ceiling for an offshore liability would be 4,400 pounds, in each case on top of the tax and the daily interest. The same guide says penalties are usually lower for voluntary disclosures and that the statutory ranges sit in HMRC factsheets, so these are upper bounds on invented figures and not a forecast of a penalty.

The income side, which the sale page does not cover

A letter about "trading in cryptoassets" can also concern tokens you received. HMRC's receiving guidance (updated April 28, 2025) says that tokens received as pay from an employer are subject to Income Tax and National Insurance on their value, and that for mining, staking, lending and decentralised finance, unless you are carrying on a trade, "HMRC will treat the tokens as other taxable income." It mentions Income Tax and not National Insurance for those. Tokens you buy yourself are not taxed on purchase, and a later sale is a Capital Gains Tax matter on "any increase in the value of the tokens since you received them."

Two numbers from that page matter for small receipts. The trading and miscellaneous income allowance is 1,000 pounds a tax year, and crypto income counts toward it; the page says to contact HMRC if total miscellaneous income is between 1,000 and 2,500 pounds, and to register for Self Assessment above 2,500 pounds. The page does not state a rule for fixing the sterling value at receipt, though it requires you to keep "separate records for the tokens you receive," including the token, the date, the number received, the total held and the pound value, and it notes HMRC may ask for them during a compliance check. A person who staked for a few years and never sold therefore has a different tax question from a person who sold and never reported, and the letter does not say which one it is addressing.

What an offer has to contain, and the clocks that start

The disclosure page sets out a sequence with fixed intervals:

On penalties the page gives no percentages. It refers to HMRC factsheets. The general disclosure guide, updated October 15, 2026, states the ceilings: "100% of the tax liability if the income or gain arose in the UK" and 200 percent for an offshore liability, with penalties usually lower for voluntary disclosures. It adds that for a disclosure that took a significant period to make, defined as over 3 years or shorter where it covers a longer period, HMRC is "unlikely that we'll reduce your penalty by more than 10 percentage points above the minimum of the statutory range." The statutory ranges themselves are not on that page, so they are not reproduced here.

What a late return costs: a stated example

If the issue is a late Self Assessment return and not a disclosure, GOV.UK's January 9, 2024 reminder for cryptoasset users lists the penalties. They were an initial 100 pound fixed penalty, daily penalties of 10 pounds a day up to 900 pounds after three months, a further penalty of 5 percent of the tax due or 300 pounds, whichever is greater, at six months and again at twelve, and late payment penalties of 5 percent of the tax unpaid at 30 days, six months and twelve months. These were the figures on that page on that date and should be checked against current GOV.UK guidance.

Suppose a person owes 2,000 pounds of tax that is paid and filed twelve months late. On the January 2024 figures, the filing penalties are 100 + 900 + 300 + 300 = 1,600 pounds, because 5 percent of 2,000 is 100 pounds, below the 300 pound floor at both the six- and twelve-month stages. The payment penalties are 5 percent of 2,000 three times, or 300 pounds. Together that is 1,900 pounds, on top of the 2,000 in tax and interest. The example is a calculation on invented inputs and it ignores reasonable excuse, which the page says may avoid a penalty. Its purpose is to show that the fixed floors dominate on small amounts, and that filing late can cost nearly as much as the tax. A disclosure for earlier years follows different rules, and the 1,900 pounds should not be read as a disclosure penalty.

Why the letters are arriving: the data flows

Three data routes appear in HMRC's own pages. Some exchanges give customers reports of their transactions, which HMRC says are not tax calculations. From January 1, 2026, anyone using a UK service to buy, sell, transfer or exchange cryptoassets must give the provider identifying details: name, date of birth, address, and a tax identification number such as a National Insurance number or Unique Taxpayer Reference. Inaccurate, missing or incomplete details can bring a penalty of up to 300 pounds. The page ties this to "an international agreement to share information between countries," and says that if you live in the UK and use a non-UK provider, that country's tax authority may share your information with HMRC under the same rules.

The provider side is laid out in the guidance for cryptoasset service providers, updated June 3, 2026. Each year reports are due by May 31, the first report covers the 2026 calendar year and is due between January 1 and May 31, 2027, and a provider may be charged up to 300 pounds per user for a failure to report, a late report or an inaccurate one. For each user who is resident in the UK or in a country that has signed up to the Crypto-Asset Reporting Framework, the provider reports the user's details and a summary of their transactions.

So the letters of 2026 arrive before the first of those reports has been filed, and the 2027 reports will not be the cause of them. HMRC's pages do not say what data is behind any individual letter, and no source read for this article says either, so a recipient cannot infer from a letter what HMRC holds. The UK tax guide on this site explains how the pooling and matching rules decide a gain, and the travel rule guide covers the identity data exchanges already collect on transfers.

Records, and who to ask

The records that matter are the ones the tax calculation needs: for each disposal, the date, the number of units, the sterling value at that date and the cost, along with any income received in tokens. HMRC's own pages do not prescribe a format. The Cryptoassets Manual (updated November 28, 2025, with sections on individuals, businesses, DeFi and compliance) is the technical reference HMRC staff use, and it is public. Questions about a disclosure can go to the helpline number on the disclosure page, 03000 55 22 94, open Monday to Thursday 9am to 5pm and Friday 9am to 4:30pm. For anything involving a deliberate omission, offshore holdings, or an enquiry letter, a qualified tax adviser is the proper next step, and this page is not a substitute for one.

Frequently Asked Questions

Is an HMRC letter about crypto a tax bill?

Not on the pages read for this article. HMRC describes the contact as a letter, email or text that links to guidance on checking that you have declared crypto activity correctly. A tax liability arises from your own disposals and income, assessed through a return or a disclosure, not from the contact message itself.

How can I tell if the message is genuine?

HMRC advises checking a contact against its list of genuine contacts and using official helplines, and says it may write before following up by email, call or text. The cryptoassets entry says the text message directs you to GOV.UK guidance. Type gov.uk addresses yourself instead of using links in unexpected messages, and report suspicious contacts through GOV.UK.

Do I have to reply?

The cryptoassets entry on the genuine contact page lists no required response and no deadline. If you have not declared crypto gains or income that should have been declared, HMRC's disclosure page says that if you do not contact it, you could be liable to additional interest and penalties.

How many years back could I have to go?

It depends on why the tax was unpaid. HMRC's disclosure guidance gives a maximum of 4 years in total if you took reasonable care (the previous year on its return plus the 3 years before it), a maximum of 6 if you did not (the previous year plus the 5 years before it), and a maximum of 20 for a deliberate failure. Confirm the exact years with HMRC or an adviser before calculating an offer.

What is the penalty for unpaid crypto tax?

HMRC's disclosure guide states a ceiling of 100 percent of the tax if the income or gain arose in the UK and 200 percent for an offshore liability, with penalties usually lower for voluntary disclosures. The statutory ranges are in HMRC factsheets that were not part of the pages read for this article.

Will exchanges report me to HMRC?

From January 1, 2026, UK cryptoasset service providers must collect user details and report them to HMRC. The first report covers calendar year 2026 and is due between January 1 and May 31, 2027. Non-UK providers in countries that have signed up to the same framework may share information with HMRC through their own tax authorities.

Can I use the disclosure route for last year's gain?

No. HMRC's disclosure page says income or gains from the current or previous tax year go on your Self Assessment return instead of through the disclosure. Earlier years with unpaid tax are the ones the disclosure route is for.

Sources

CryptosEyes publishes general educational research, not investment, legal, or tax advice. This article summarizes published HMRC guidance as of the dates stated and applies none of it to any person's facts. Rules, rates and penalties change; check current GOV.UK pages or consult a qualified tax adviser before responding to HMRC.