240 filers booked half of Britain's £1.38bn of declared crypto gains
The first year with a crypto box on the Self Assessment return shows a base narrow enough to fit in one room. That changes both what a rate rise would collect and what the 2027 exchange data feed is worth chasing.
The Investor · Invest desk
What happened
- HMRC broke cryptoasset gains out of the general capital gains figures for the first time, covering 2024-25, the first year the Self Assessment return carried a dedicated crypto disposals section.
- Some 17,600 individuals declared £13.8bn of crypto disposal proceeds and £1.38bn of taxable gains for the year, an average gain of £78,000 per filer.
- A cluster of 240 filers each cleared more than £1m of crypto gains, and between them they took £717m of the total.
- The 65% of crypto taxpayers who reported gains under £25,000 accounted for just 7% of the gains and 8% of the disposal proceeds.
- HMRC sent 81,000 nudge letters to suspected underpayers over the past year, up 25% on about 65,000, and from 31 May 2027 expects automatic reports on UK residents from exchanges in 52 jurisdictions.
Why it matters
- What it limits constraint With 51.96% of the declared yield sitting on 240 identifiable returns, any change to the crypto CGT rate is priced off a cohort small enough that individual departures move the revenue line.
- Who has to decide decision HMRC now has to choose whether the incoming provider data is worked as a volume campaign against four-figure liabilities or as a reconciliation exercise on the filers who already hold the money.
- Who's exposed exposure Once provider reporting is automatic, the disclosure window for non-filers stops depending on whether a letter arrives and starts closing on a calendar date set outside HMRC.
- What it sets up precedent A first official profile that is overwhelmingly male and mostly under 55 hands future crypto tax proposals a distributional argument that has nothing to do with how much revenue is at stake.
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The conversion rate is where this data earns its keep. £13.8bn of disposals produced £1.38bn of taxable gains [1], a margin of 10.0% [20], which means roughly £12.42bn of that gross flow was cost basis coming back out again [21], and since swapping one cryptoasset for another is itself a disposal [15], some unknown slice of the £13.8bn never touched sterling.
Split it by age and the spread widens. The 25 to 44 band supplied 71% of proceeds and kept 45% of the gains [10], which works out at a 6.3% margin against 19.0% for everyone 45 and over [25][26], so the group doing most of the volume converts at about a third of the older group's rate [27]. Men were 87% of filers and took 93% of the gains [12].
Below the millionaires the distribution is unremarkable. Strip out the 240 and the remaining 17,360 filers shared £663m, or £38,190 each [23], against £2.9875m each at the top [22], a gap of 78 to one [24]. The 65% reporting under £25,000 come to about 11,440 people [28] holding £96.6m of gains between them, £8,444 apiece [29]. And because HMRC puts more than half of the proceeds with the same 240 [8], their own conversion margin is at most 10.4% [19], so what separates them is size rather than edge.
That is the figure that should govern enforcement design, and does not appear to. The 81,000 nudge letters sent in the past year, on UHY Hacker Young's count [3], outnumber the people who actually filed a crypto disposal by 4.6 to one [13], and letter volume has gone from 27,714 in 2023-24 [4] to 81,000, a 2.9-fold rise in two years [14]. Every one of those letters is officer time not spent reconciling the 240 returns that hold half the money.
This is probably wrong, but the provider data HMRC expects in 2027 [5] looks likelier to surface a very large number of four-figure liabilities than a second cohort of millionaires, and four-figure liabilities are expensive to collect one at a time. The counter-thesis, which is roughly what Neela Chauhan of UHY Hacker Young means when she says investigations will be "like shooting fish in a barrel" once the data lands [30], is that the declared distribution measures who knew to fill in the new box rather than who made the money, and the missing middle sits offshore where a 2024-25 return could not reach it.
Two results would break my read. If the 2027 provider data shows undeclared gains averaging anything close to the £78,000 mean of declared filers [1] rather than the tail's £8,444 [29], the volume campaign is aimed correctly and the arithmetic above is a distraction. And if roughly 240 millionaire filers turn up again next year, HMRC is taxing a standing base rather than one cycle's exits, or rather, the more interesting version of that: a standing base of 240 people who can change residence faster than the Treasury can rewrite a rate.
What to watch
- Whether HMRC publishes disposal proceeds for the 240 millionaire filers, which would fix their conversion margin instead of leaving it bounded at 10.4%.
- The 31 January 2027 payment deadline for 2025-26 gains, the last fully self-declared year before provider reporting begins.
- Whether the 15 further jurisdictions joining in 2028 cover the venues the declared middle of the distribution is currently missing from.
Information, not investment advice. This story is general information about companies and markets, drawn from cited reporting. It is not a recommendation to buy, sell or hold any security; check the cited sources before acting.
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Reality
- Evidence78
- Adoption58
- Hype gap+14
- Incentives66
- Confidence71
Perspective Coverage
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- [1]
For 2024-25, 17,600 individuals filed taxable crypto asset capital gains, reporting £13.8bn in disposal proceeds and £1.38bn in total gains, an average gain per individual of £78,000.
- [2]
HMRC said 240 people each reported more than £1m in crypto capital gains during 2024-25, with that millionaire cohort accounting for £717m of the total gains.
- [3]
HMRC sent 81,000 nudge letters to crypto investors it suspected had underpaid tax in the past year, up 25% from 65,000 a year earlier, according to accountancy firm UHY Hacker Young.
- [4]
HMRC sent 27,714 nudge letters of this kind in 2023-24.
- [5]
The UK began implementing the OECD's Cryptoasset Reporting Framework in January 2026, and HMRC said it will start receiving customer data from crypto asset service providers in 2027.
- [6]
From May 31, 2027, HMRC is expected to automatically receive information on UK residents from crypto exchanges in 52 jurisdictions, with another 15 jurisdictions expected to begin providing information in 2028.
- [7]
HMRC split cryptoasset gains out from the rest of the capital gains figures for the first time, covering the 2024-25 tax year, which was the first year the Self Assessment return carried a dedicated section for cryptoasset disposals.
- [8]
The 240 millionaire filers are less than 2% of all those who reported a crypto disposal, and HMRC's commentary ascribes more than half of the gains and of the £13.8bn of disposal proceeds to them.
- [9]
65% of crypto taxpayers reported gains of under £25,000, and that majority accounted for only 7% of the gains and 8% of the proceeds.
- [10]
71% of all proceeds from crypto disposals came from people aged 25 to 44, but that age group took only 45% of the gains.
- [11]
54% of crypto taxpayers are in the 25-44 age band, compared with 17% of capital gains taxpayers overall, and 81% are aged 54 or under.
- [12]
87% of those reporting crypto gains were men, versus 56% across the broader capital gains population, and they booked 93% of the gains.
- [13]
HMRC's 81,000 nudge letters outnumber declared crypto disposal filers by 4.6 to one.
- [14]
Nudge letter volume rose 2.9-fold in two years.
- [15]
Taxable events for the HMRC figures include selling crypto, exchanging one cryptoasset for another, using crypto to pay for goods or services, and certain gifts.
- [16]
For the 2025-26 tax year, taxpayers with crypto income or gains above the applicable tax-free allowance must report them through Self Assessment and pay any tax due by Jan. 31, 2027.
- [17]
The 240 millionaire filers took 51.96% of all declared crypto gains.
- [18]
The 240 millionaire filers were 1.36% of the 17,600 filers.
- [19]
Because more than half of the £13.8bn of proceeds belongs to the 240, their own conversion margin is at most 10.4%.
- [20]
Declared gains were 10.0% of declared disposal proceeds.
- [21]
The gap between proceeds and gains implies about £12.42bn of cost basis returned in the year's disposals.
- [22]
Average gain within the millionaire cohort was £2.9875m per filer.
- [23]
The other 17,360 filers shared £663m of gains, an average of £38,190 each.
- [24]
The millionaire cohort's average gain is 78 times the average of every other filer.
- [25]
The 25-44 band converted proceeds to gains at a 6.3% margin.
- [26]
Filers aged 45 and over converted proceeds to gains at a 19.0% margin.
- [27]
The older cohort's conversion margin is about three times the 25-44 band's.
- [28]
The 65% of filers reporting under £25,000 of gains number about 11,440 people.
- [29]
That sub-£25,000 group holds about £96.6m of gains, an average of £8,444 each.
- [30]
Neela Chauhan, a partner at UHY Hacker Young, said that once HMRC has the data, tax investigations into cryptocurrency investors "will be like shooting fish in a barrel", and that with basic AI software HMRC will be able to build a comprehensive list of investors behind on CGT or income tax.
Sources
3 independent publishers whose own reporting we read for this story.
- cointelegraph.comUK government reports 240 crypto millionaires in 2025
1 article · August 27, 2026
- cryptopolitan.comFirst HMRC crypto figures show a young, male minority booking most of the gains
1 article · August 28, 2026
- theblock.coLatest annual UK tax data shows 240 people reported more than £1 million in crypto capital gains
1 article · August 28, 2026
Topics and entities
Topics
- Crypto tax enforcement
- UK crypto taxation
- Capital Gains Tax
- Cross-border tax data sharing
Entities
- Cryptoasset Reporting Framework
- OECD
- UHY Hacker Young
- HM Revenue and Customs