Crypto Tax for US Citizens in the UK: Both Sides

Crypto tax for US citizens in the UK means reporting the same assets twice: to the IRS and to HMRC. The US taxes your worldwide crypto gains and income and asks the digital-asset question on Form 1040; the UK taxes the same disposals under its own rules. Foreign tax credits relieve most double taxation.

If you are an American living in the UK with a meaningful crypto position, you sit between two assertive tax authorities that measure the same coins differently, on different calendars, in different currencies. Handled well, you pay the higher of the two bills once; handled badly, you risk penalties on both sides.

Key takeaways

• You report on both sides. US citizenship is taxed on worldwide income and gains regardless of where you live, and UK residence brings the same crypto within HMRC's rules — so the same transactions are declared to the IRS and to HMRC.
• The rules genuinely differ. The US treats crypto as property and now requires basis to be tracked wallet by wallet; the UK uses same-day, 30-day and pooled (Section 104) matching to compute each disposal. The numbers rarely line up cleanly.
• Foreign tax credits do the heavy lifting. Relief under the US-UK treaty and each country's foreign tax credit rules is what stops you paying full tax twice, but it has to be claimed correctly and by the right country first.
• Mining and staking can pull in US self-employment tax. If the activity amounts to a trade or business, that is a liability the foreign earned income exclusion does not touch.
• Losses behave differently in each country. The US lets a net capital loss shelter a slice of ordinary income; the UK does not.
• Exchange accounts raise an FBAR/Form 8938 question. Whether an offshore crypto exchange account is a reportable foreign financial account is an unsettled, fact-specific area — often best handled conservatively.
• Records are everything. Because two regimes value the same wallet differently, disciplined dual-currency record-keeping is the difference between a clean filing and a costly reconstruction.

What does crypto tax for US citizens in the UK actually involve?

The reason crypto tax for US citizens in the UK is so involved is that two independent systems apply to one set of transactions. The United States taxes its citizens on worldwide income and gains no matter where they are resident. The United Kingdom taxes people who are UK-resident on their gains and, in most cases, their worldwide income. If you are a US citizen resident in the UK, you fall squarely inside both nets.

That does not mean you pay twice in full. You calculate the tax twice, under two rulebooks, then use relieving mechanisms so the same gain is not taxed in full by both. But the calculation, reporting and timing are separate exercises, and the mismatches between them are where the real work lies.

How does the US tax your crypto?

The IRS treats cryptocurrency as property, not currency. Every disposal — selling for pounds or dollars, swapping one token for another, or spending crypto on goods and services — is a potentially taxable event that produces a capital gain or loss. Being paid in crypto, and rewards from activities such as staking or mining, are generally treated as ordinary income at the value received. The IRS sets out the framework on its digital assets pages, and every Form 1040 now carries a digital-asset question you must answer truthfully.

Two US-specific nuances matter for anyone crypto-active in the UK:

• No like-kind exchanges. Since the 2017 tax reform, the Section 1031 like-kind exchange rules apply only to real property. Swapping Bitcoin for Ether is therefore a taxable disposal in the US, even though no cash changed hands.
• The wash-sale rule and crypto. Under current US rules the wash-sale rule bites on "stock or securities." Because crypto is treated as property, selling at a loss and rebuying shortly after has not historically been caught the way it is for shares. This has been a repeated target for legislative change, so it should be confirmed, not assumed.

Holding period drives the US rate. Assets held longer than a year are generally taxed at the long-term capital gains rates — the IRS sets these at 0%, 15% or 20% depending on your taxable income, with higher maximum rates for collectibles and certain other assets — while short-term gains are taxed as ordinary income at graduated rates. The income thresholds that separate those bands change every year, so confirm the current figures before you plan around them.

One assumption worth killing early: the foreign earned income exclusion does nothing for a crypto gain. It applies to foreign earned income, which the IRS defines as "wages, salaries, professional fees, or other amounts paid to you for personal services rendered by you." A profit on a token sale is not pay for services. If you have been assuming the exclusion covers your whole US position, our comparison of the exclusion and the foreign tax credit is the place to start.

How does HMRC tax the same crypto?

HMRC also does not treat crypto as money. For most individual investors, buying and selling cryptoassets falls under Capital Gains Tax, while crypto received as employment income, from mining, or from staking is usually taxed as income. HMRC's guidance on paying tax when you sell cryptoassets is the starting point.

Where the UK diverges sharply from the US is in how the gain is measured. Rather than tracking each lot separately, HMRC applies a sequence of matching rules: a same-day rule, then a 30-day rule (to stop "bed and breakfasting" a loss), and finally a Section 104 pool that blends everything else into a single average cost per token. A disposal that produces one figure under US accounting can produce a materially different figure under UK pooling of the very same coins. Neither is wrong; they are simply different rulebooks, and the annual exempt amount and CGT rates that apply are set by the UK and change over time.

The two regimes have recently moved further apart rather than closer. Under the US final regulations on digital assets, basis has to be identified per wallet or per account, and Revenue Procedure 2024-28 gave taxpayers a route to allocate unused basis across the units held in each wallet or account as of 1 January 2025. HMRC's pool runs in the opposite direction: one pooled cost per token type across everything you hold, wherever you hold it. If you have the same coin spread across three exchanges and a hardware wallet, the US now wants four separate basis histories and HMRC wants one blended figure. Trying to derive either from the other after the fact is the single most expensive mistake in this area.

HMRC's allowable-cost rules add another small divergence worth knowing. Transaction fees, valuation costs and a proportion of the pooled cost are deductible against a UK gain — but mining costs such as equipment and electricity are explicitly not. That is close to the opposite of the US position for someone genuinely mining as a business.

Mining, staking and the self-employment tax trap

If your mining or staking is a hobby, the income is reported and that is broadly the end of it. If it rises to a trade or business, the US adds a second layer that catches a lot of people by surprise: self-employment tax at 15.3%, made up of 12.4% for social security and 2.9% for Medicare, payable once net earnings from self-employment reach $400. The social security portion applies only up to an annual ceiling; the Medicare portion applies to all of it.

This matters disproportionately for Americans in the UK for two reasons. First, the foreign earned income exclusion reduces regular income tax but not self-employment tax, so the usual expat shield does not help here — the detail is in our guide to paying US self-employment tax while self-employed in the UK. Second, the US-UK social security agreement is what normally determines which country's system you contribute to, and a certificate of coverage is how you prove it; see US-UK certificates of coverage and totalisation. Whether your mining is a business at all is a facts-and-circumstances question on both sides of the Atlantic, and it is worth settling before you file rather than after.

How does the foreign tax credit stop double taxation?

This is the mechanism that makes the whole thing workable. Broadly, one country taxes the gain and the other gives credit for that tax, so you end up paying roughly the higher of the two rates rather than the sum. The US allows a foreign tax credit for income taxes paid to the UK, and the US-UK double tax treaty allocates taxing rights between the two.

The complications are real: which country has the primary right to tax a given gain, and how timing differences (the US tax year is the calendar year; the UK year ends 5 April) can strand a credit in the wrong period. Getting the ordering wrong is the most common way expats accidentally overpay, and excess credits do not simply vanish — our guide to foreign tax credit carryovers explains where they go. Modelling both returns together, in the right sequence, is exactly what our US-UK expat tax accountants do before anything is signed.

What happens to a loss on each side?

Crypto losses are where the two systems diverge in a way that genuinely changes the cash outcome, and it is worth knowing before you decide when to crystallise one.

On the US side, capital losses offset capital gains, and if your losses exceed your gains you can deduct the lower of $3,000 ($1,500 if married filing separately) or your total net loss against other income, with the excess carried forward to later years. That ability to shelter a slice of ordinary income has no UK equivalent: in the UK, capital losses reduce capital gains, and HMRC requires you to report a loss before you can use it. Claim late and the relief can simply be gone.

The practical consequence is that a single loss can be worth more on one return than the other, and a disposal timed near either year end — 31 December for the US, 5 April for the UK — can land in different tax years in the two countries. Our guide to capital losses across the US and UK covers the sequencing.

Which forms carry the numbers on each side?

The reporting routes are entirely separate, and neither authority accepts the other's paperwork.

On the US return, disposals of crypto held as a capital asset go on Form 8949, Sales and Other Dispositions of Capital Assets, and feed the capital gains schedule. Ordinary income from forks, staking and mining goes on Schedule 1, and if the activity is a business it goes on Schedule C instead. On the UK side, HMRC gives you two routes: the cryptoasset section of the Self Assessment return, which has existed from the 2024 to 2025 tax year onwards, or the Capital Gains Tax real time service during the year. Everything on the UK return is reported in pounds sterling; everything on the US return in US dollars. If Self Assessment is new to you, who must file and how to avoid penalties sets out the mechanics.

A second reporting change is now feeding the IRS data directly. US brokers must report digital-asset transactions on the new Form 1099-DA, covering gross proceeds for transactions effected on or after 1 January 2025 and, for certain transactions, basis from 1 January 2026. A UK or offshore exchange generally will not issue one. That cuts both ways: there is no third-party form arriving to check your figures against, and no form for the IRS to match either — so the entire burden of getting it right, and of being able to show your working years later, sits with you.

One more obligation that outlives a move abroad: if you left a US state with a sticky residency rule, a crypto gain may still sit in that state's net even though you now live in London. Our guide to state tax for US expats in California and New York covers the states that are hardest to leave.

Do I report crypto exchange accounts on FBAR and Form 8938?

Separately from the tax on gains, US persons must disclose foreign financial accounts. The FBAR (FinCEN Form 114) is triggered when the aggregate value of your foreign financial accounts exceeds $10,000 at any point in the calendar year — a threshold most crypto-active expats cross on the fiat side alone. Cash and securities held at a UK bank or broker are clearly reportable, and above the relevant thresholds on Form 8938 as well. Whether an account at an offshore crypto exchange is itself a reportable foreign financial account has been a moving, unsettled question rather than a clearly resolved one.

Because the downside of under-reporting a foreign account is severe and the cost of disclosing is low, many advisers disclose where there is doubt. This is a fact-specific call that should be reviewed by a specialist rather than guessed. It sits alongside the fund-reporting traps in our companion guide to PFIC tax rules for US investors abroad, which catch many of the same people.

What records do you need for both regimes?

Good record-keeping is the single highest-return habit for anyone facing crypto tax for US citizens in the UK. You are keeping one ledger that has to satisfy two authorities:

• Every transaction, in both currencies — date, type, quantity and value in both US dollars and pounds sterling, because each regime reports in its own currency.
• A timestamp you can defend — the date and time of each transaction, recorded consistently in UTC. With a US year ending 31 December and a UK year ending 5 April, a trade near either boundary needs to land in the right year on the right return, and "sometime that week" is not good enough.
• Cost basis under both methods — US basis tracked per wallet and per account, and UK pooled (Section 104) cost, so neither return has to be reverse-engineered from the other.
• Income events flagged separately — staking, mining, airdrops and crypto pay are income, valued when received.
• The identifying detail — exchange or platform, transaction ID or hash, and the counterparty on any peer-to-peer transfer. Transfers between your own wallets are not disposals, but they have to be documented as transfers or they look like sales.
• A full exchange and wallet inventory — needed for the tax computations and the FBAR/Form 8938 assessment.

Specialist tracking software helps, but rarely produces a correct US and UK view out of the box, and it will not resolve a basis history you never recorded. Currency movements add their own layer, which our guide to cross-border currency gains and losses explains. You can pressure-test your numbers against our cross-border global tax calculator before a professional finalises the figures.

If you have been crypto-active for several years and have not been reporting on one or both sides, the priority is an orderly catch-up rather than a rushed filing. Where the omission was non-wilful, US expats can usually regularise multiple years together — see our guide to missed US tax returns. The sooner the history is reconstructed, the more options you have.

Every position we prepare is reviewed and signed by our licensed professional — an IRS Enrolled Agent who is also ACCA-qualified, covering both sides of the filing. If you would like your specific holdings reviewed on both sides, book a consultation or review our pricing first.

Reviewed by an IRS Enrolled Agent who is also ACCA-qualified

This article is general information, not personal tax advice. Crypto tax rules, rates, allowances and reporting thresholds change frequently in both the US and the UK, and the treatment of individual transactions is fact-specific. Confirm your own position with a qualified professional before acting.