HMRC Crypto Tax: Same Day and 30 Day Rules Explained

You trade on three exchanges. One morning you buy ETH on one of them, and that afternoon you sell some on another. Two weeks later you buy back in. Each exchange gives you a tidy CSV. None of them gives you your tax figure, and under HMRC's rules you cannot get one by adding the CSVs together.

This guide covers what UK traders need for the current tax year: the allowance, the rates, what counts as a disposal, and the matching rules that catch out active traders, with a worked example.

The numbers for 2026 to 2027

• Annual exempt amount (the tax-free allowance): £3,000 for individuals.
• Capital Gains Tax rates from 6 April 2026: 18% on gains that fall within your basic rate band, 24% on gains above it. Higher and additional rate taxpayers pay 24% on all their gains.
• The tax year runs from 6 April to 5 April.

Your gains, less the allowance, are added to your taxable income to see how much falls in the basic rate band. That is why two people with the same crypto gain can pay different amounts.

What counts as a disposal

You may have to pay Capital Gains Tax when you dispose of cryptoasset tokens. HMRC lists these disposals:

• selling tokens
• exchanging tokens for a different type of cryptoasset
• using tokens to pay for goods or services
• giving tokens away, unless it is a gift to your spouse, civil partner or a charity

The second one catches many traders. Swapping BTC for ETH is a disposal of the BTC. You do not need to cash out to pounds to make a taxable gain.

Moving tokens between wallets you control is not a disposal, as long as you keep beneficial ownership. Keep the records that link the withdrawal to the deposit.

Pooling and the matching rules

You do not get to choose which tokens you sold. HMRC applies the same matching rules as for shares. Each type of token has its own pool: one for BTC, one for ETH, and so on. The pool is per token type, not per exchange.

When you dispose of tokens, they are matched in this order.

1. The same day rule

Tokens of the same type acquired on the same day as the disposal are matched first. All acquisitions of that token on one day count as one acquisition, and all disposals that day count as one disposal.

2. The 30 day rule (bed and breakfasting)

Next, tokens of the same type that you acquire in the 30 days after the disposal are matched to it, earliest disposal first. HMRC's manual calls this the 30-day rule. Traders often call it bed and breakfasting.

3. The Section 104 pool

Whatever is left is matched to the pool. The cost is the pool's average: the pooled allowable cost divided by the number of tokens in it.

Tokens matched under the first two rules never enter the pool.

Worked example

Priya trades ETH on two exchanges. All figures are made up for illustration, and fees are left out to keep it simple.

• Before the tax year: her Section 104 pool holds 10 ETH with a pooled cost of £15,000 (£1,500 each).
• 1 August 2026, morning, Exchange A: buys 2 ETH for £5,000.
• 1 August 2026, afternoon, Exchange B: sells 3 ETH for £7,800 (£2,600 each).
• 20 August 2026, Exchange A: buys 1 ETH for £2,200.
• 10 December 2026, Exchange B: sells 4 ETH for £12,000. She buys no ETH in the 30 days after.

The 1 August disposal (3 ETH, £7,800):

Same day rule: 2 ETH are matched with the 2 ETH bought that morning, even though they were on a different exchange. Proceeds £5,200, cost £5,000, gain £200.

30 day rule: the remaining 1 ETH is matched with the 1 ETH bought on 20 August, 19 days later. Proceeds £2,600, cost £2,200, gain £400.

Pool: nothing is left to match, so the pool stays at 10 ETH and £15,000.

Gain on 1 August: £600.

The 10 December disposal (4 ETH, £12,000):

There is no same day purchase and no purchase in the next 30 days, so all 4 ETH come from the pool. Cost: 4 × £1,500 = £6,000. Gain: £6,000. The pool is left with 6 ETH and a pooled cost of £9,000.

Total gains for the year: £6,600. After the £3,000 allowance, £3,600 is taxable, at 18% or 24% depending on your income.

Now the multi-exchange problem. Exchange A's report shows two purchases and no sales. Exchange B's report shows two sales and no matching purchases. Neither exchange can apply the same day or 30 day rule, because each sees only half of the trades. HMRC itself says exchange reports are not tax calculations and do not track pooled costs.

Fees and allowable costs

Some costs reduce your gain. HMRC accepts, for example, transaction fees paid to have a transaction recorded on the blockchain, and exchange fees for buying tokens with pounds or selling them for pounds. For a token to token swap, HMRC accepts a 50/50 split of the fee between the two tokens. Fees for depositing or withdrawing pounds are not allowable.

Income vs capital: staking and airdrops

Not every token you receive is just a capital gains question.

Staking: if your activity is not a trade, HMRC treats staking rewards as miscellaneous income, valued in pounds at the time you receive them. If you keep the tokens, you may also pay Capital Gains Tax when you dispose of them later.

Airdrops: tokens you get in return for, or in expectation of, a service are taxed as income. Tokens received without doing anything in return, and not as part of a trade, may not be subject to Income Tax. A later disposal can still create a chargeable gain.

If your trading is organised and frequent enough to count as a trade, different rules can apply. That is a question for an adviser.

Reporting and the deadline

You must report if your total gains for the year are above the allowance. The Capital Gains Tax summary pages (SA108) also have to be filled in if you disposed of chargeable assets worth more than £50,000, even when there is no tax to pay. Since the 2024 to 2025 tax year, SA108 has its own cryptoasset section. It asks for the number of disposals, the proceeds, the allowable costs, and your gains and losses.

The online Self Assessment deadline for the 2025 to 2026 tax year is 31 January 2027. You can also report through HMRC's real time Capital Gains Tax service.

The records HMRC expects

For each pool, HMRC says to keep a separate record of each transaction:

• the type of token
• the date you disposed of it
• the number of tokens you disposed of
• the number of tokens left
• the value of the tokens in pounds sterling
• bank statements
• the pooled cost before and after the disposal

HMRC can ask for these in a compliance check. Wallet addresses are useful too.

CARF: exchanges now report to HMRC

The UK's rules for the OECD Cryptoasset Reporting Framework (CARF) came into effect on 1 January 2026. UK cryptoasset service providers have to collect information about their users and their transactions. Their first report to HMRC is due between 1 January and 31 May 2027. The government has extended the reporting to UK-resident customers, and information about non-UK users is exchanged with other tax authorities.

In practice, HMRC will hold data it can compare with your return. Your figures need to add up across every exchange you use.

How TheCryptoHub helps

Connect your exchanges with read-only or trade API keys, never withdrawal permission, and TheCryptoHub builds one P&L across all of them. Transfers between your own accounts are matched, so they are not counted as disposals.

For the UK, the Tax Center applies HMRC's matching order, same day first, then 30 days, then the Section 104 pool, across all your connected exchanges at once. It produces the SA108 cryptoasset figures and shows the matching for each disposal, so you or your accountant can check every line.

Try it on sample data first, with no signup: open the free demo.