UK Crypto Capital Gains Tax: Same-Day, 30-Day and Section 104 Rules

UK crypto gains are not calculated with global FIFO. For fungible tokens held in the same capacity, HMRC generally applies a strict matching order: acquisitions on the same day, acquisitions in the following 30 days, then the Section 104 pool. Applying an average cost before those first two rules can materially change a gain or loss. This guide explains the 2025/26 and 2026/27 rules with a practical workflow.

Short answer: how UK crypto gains are calculated

HMRC generally treats tokens held as investments as chargeable assets. An individual can make a disposal by selling tokens, exchanging one token for another, spending them, or giving them away to someone other than a spouse, civil partner or qualifying charity. The gain is broadly the sterling value received less the matched allowable cost and deductible transaction costs.

For fungible tokens dealt in without identifying particular units, calculate cost in this order:

1. Match acquisitions and disposals of the same token made on the same day and in the same capacity.
2. Match the remaining disposal with acquisitions of the same token made in the following 30 days.
3. Match any remaining quantity to the average allowable cost in that token's Section 104 pool.

The 30-day rule looks forward from a disposal. It is not a choice and it is not simply “use FIFO.” A tax calculation produced on the sale date may therefore need to remain provisional until the following 30 days have passed.

UK crypto CGT rates and annual exempt amount

For individuals, the ordinary Capital Gains Tax rates applying to cryptoasset investment gains are 18% and 24% for both the 2025/26 and 2026/27 tax years. The portion using the unused basic-rate band is charged at the lower rate; the balance is charged at the higher rate. Taxable income must therefore be considered before a final CGT rate can be calculated.

The annual exempt amount for most individuals is £3,000 in both years. It applies after allowable losses and relevant reliefs are considered. It is not a per-token or per-exchange allowance. A person claiming the foreign income and gains regime or Overseas Workday Relief does not receive the annual exempt amount for that year.

• 2025/26: 6 April 2025 to 5 April 2026; individual AEA £3,000; ordinary individual rates 18% and 24%.
• 2026/27: 6 April 2026 to 5 April 2027; individual AEA £3,000; ordinary individual rates 18% and 24%.
• Not a flat tax: one taxpayer can pay both rates because taxable gains sit on top of taxable income.

“2026 crypto tax” is ambiguous. A disposal on 1 March 2026 belongs to 2025/26; a disposal on 1 September 2026 belongs to 2026/27. Reports should be filtered by the UK tax year, not the calendar year.

Which crypto events are disposals?

• Selling BTC, ETH or another token for GBP or foreign currency.
• Swapping one cryptoasset for another, including a stablecoin.
• Using tokens to pay for goods, services, gas or another asset.
• Giving tokens to another person, subject to spouse/civil-partner and charity rules.
• Receiving money or another asset when redeeming or closing a tokenised position.

Buying tokens with pounds is normally an acquisition, not a gain. Moving tokens between wallets beneficially owned by the same person is normally not a disposal, but the transfer must be linked so that the Section 104 pool is not duplicated. A network fee paid in tokens requires separate analysis because tokens have been disposed of to obtain the transfer service.

A transfer between spouses or civil partners living together normally uses the no-gain/no-loss rule, not a tax-free market-value reset. The recipient needs the carried cost. A gift to another connected person can require market value even when no cash is received.

Tokens received as staking, mining, employment or DeFi income can create Income Tax first. If they are later disposed of, CGT is calculated on the change from the value already brought into income, subject to the normal matching rules. The same receipt must not be taxed twice as both zero-basis gain and income.

Same-day and 30-day matching in detail

HMRC's same-day rule aggregates acquisitions of a particular token on a day and aggregates disposals of that token on the same day. As far as possible, the two quantities match each other before either enters the Section 104 calculation.

If disposal quantity remains, acquisitions of the same token during the next 30 days are matched to earlier disposals. HMRC states that qualifying acquisitions are matched to disposals on an earliest-disposal-first basis. Only excess acquisitions that are not matched under the rule enter the Section 104 pool.

The rule applies when the person acts in the same capacity. Personal holdings, trustee holdings and business inventory must not be casually merged. Each token type has its own pool; BTC and wrapped BTC are not assumed to be one asset merely because prices track each other. A token migration, bridge or wrapper needs an asset-identity analysis.

The popular term “bed and breakfasting rule” can mislead U.S. readers. It is not the U.S. wash-sale rule and it does not mechanically disallow every crypto loss. It changes which acquisition cost is matched to the disposal. Depending on prices and quantities, that can reduce, increase or defer the apparent loss compared with using the Section 104 average.

Worked 30-day rule example

Assume an investor has a Section 104 pool of 2 ETH with pooled allowable cost of £4,000. There are no other same-day transactions.

1. On 1 June, the investor sells 1 ETH for £1,700.
2. On 20 June, the investor buys 0.6 ETH for £900.
3. The 0.6 ETH acquisition is within 30 days and is matched to 0.6 ETH of the 1 June disposal.
4. The matched portion has proceeds of £1,020 if the sale proceeds are apportioned by quantity and matched cost of £900, producing a £120 gain before allowable costs.
5. The remaining 0.4 ETH disposal is matched to the Section 104 pool. Its pooled cost is £800, producing a £120 loss on £680 apportioned proceeds.
6. The two parts net to nil before transaction costs.

The calculation is not simply £1,700 proceeds less the original £2,000 average cost. The later acquisition changed the cost matching for part of the sale. The remaining pool must then be updated with the exact quantities and costs used; rounding only at display level avoids cumulative errors.

Maintaining the Section 104 pool

A Section 104 pool is a running quantity and pooled allowable cost for each fungible token beneficially owned in the same capacity. It is not an exchange balance and not a wallet-by-wallet FIFO ledger. Moving ETH from Coinbase to a self-custody wallet does not create a new pool if beneficial ownership remains unchanged.

For each acquisition entering the pool, add the quantity and allowable sterling cost. For a pooled disposal, remove the same fraction of pooled allowable cost as the fraction of units disposed of. HMRC's example uses 200 units sold from 400 pooled units, so half of the pool cost is allocated to the disposal.

Maintain, at minimum:

• token identity, including contract address where symbols are ambiguous;
• pool quantity and allowable cost before and after every event;
• sterling value and valuation source;
• same-day and 30-day matches kept outside the pool;
• fees and whether they were already deducted elsewhere;
• income-basis amounts for tokens previously taxed as income;
• own-wallet transfer links and exchange account identifiers.

NFTs are separately identifiable and HMRC says they are not pooled under these token matching rules. LP tokens, wrapped tokens and migration receipts require an identity and rights analysis before deciding which pool—if any—applies.

Crypto losses, negligible value and record deadlines

An allowable capital loss from crypto can reduce chargeable gains under the normal rules. Current-year losses are used before the annual exempt amount; unused allowable losses can generally be carried forward once properly notified. Do not sell and rebuy without modelling the 30-day match, because the expected Section 104 loss may not be the actual result.

A token becoming illiquid, an exchange freezing withdrawals or a wallet losing market value does not automatically create a disposal. A negligible-value claim has separate conditions and timing. Lost keys, scams, bankruptcies and worthless tokens should not be converted into a capital loss without evidence and a rule-specific review.

HMRC requires taxpayers to retain their own transaction and pool records. Exchange statements can be essential evidence, but HMRC explicitly notes they are not tax calculations and do not maintain a taxpayer's complete pooled costs. Preserve the raw files even after an account closes.

Reporting crypto gains to HMRC

1. Use the UK tax year ending 5 April, not a calendar-year filter.
2. Import every exchange, wallet and protocol, including earlier history needed to build opening pools.
3. Connect own-wallet transfers and remove duplicates.
4. Convert each event to pounds using a reasonable, consistently applied valuation source.
5. Apply same-day matching across all venues.
6. Wait for and apply acquisitions in the 30 days after each disposal.
7. Apply Section 104 pooled cost to the remaining quantities.
8. Reconcile income-taxed token receipts so their cost is not omitted.
9. Net allowable gains and losses, then apply the annual exempt amount where available.
10. Report through Self Assessment or HMRC's applicable CGT reporting service and retain the detail ledger.

HMRC's Self Assessment return includes a specific cryptoasset section from 2024/25 onwards. The UK crypto tax guide covers the overall filing process; the UK loss guide covers claims and carry-forward. Exchange exports should be checked with the UK exchange-report guide. A CoinTaxReporting UK report should expose unresolved token identities and missing pool history instead of silently treating them as zero basis.

Frequently asked questions

Official sources

• HMRC: selling cryptoassets, pooling, records and reporting
• HMRC Cryptoassets Manual CRYPTO22200: same-day, 30-day and Section 104 pooling
• HMRC CRYPTO22256: worked matching example
• HMRC: Capital Gains Tax rates and annual exempt amounts
• HMRC: cryptoassets received as income
• HMRC: Self Assessment Capital Gains Summary SA108

Sources reviewed 1 September 2026. This guide covers common individual investment cases; trading businesses, trusts, residence and foreign-income claims need separate analysis.

Disclaimer: This article is for general informational purposes only and does not constitute tax advice. For individual tax advice, consult a licensed tax professional.