UK Crypto Tax 2024/25 Guide: SA108, £3K, Split-Year CGT

The 2024/25 tax year is the most complicated year for crypto tax in UK history. CGT rates changed mid-year. The annual exempt amount was halved again. HMRC introduced a dedicated cryptoassets section on the SA108 form for the first time. And from 1 January 2026, your exchange began collecting your transaction data for HMRC under the Crypto-Asset Reporting Framework, with the first reports due to HMRC by 31 May 2027.

If you bought, sold, swapped, staked, or provided liquidity with crypto at any point between 6 April 2024 and 5 April 2025, this guide is for you. It covers everything you need to file correctly, and on time.

Who needs to file a crypto tax return?

If you are registered for Self Assessment, complete the Capital Gains Summary (SA108) pages when either of these applies:

• Your total disposal proceeds from all assets (including crypto) exceed £50,000
• Your chargeable gains (before losses) exceed the annual exempt amount of £3,000

If you are not registered, the £50,000 proceeds threshold alone does not require a return. Chargeable gains above the allowance still need to be reported, using Self Assessment or HMRC's Capital Gains Tax service. You can also claim a capital loss for future use without treating the proceeds threshold as a filing obligation.

Crypto income is separate. Taxable staking rewards, mining income or conditional airdrops follow the income-reporting rules and go on the main SA100 return, not SA108. Use HMRC's checker if you are unsure whether your combined circumstances require Self Assessment.

What counts as a disposal

A disposal is any event where you "get rid of" a cryptoasset. HMRC's Cryptoassets Manual (CRYPTO22100) defines the following as disposals that trigger Capital Gains Tax:

• Selling crypto for GBP or any other fiat currency
• Swapping one crypto for another, including stablecoin swaps (e.g. ETH → USDC)
• Paying for goods or services with crypto
• Gifting crypto to anyone other than your spouse or civil partner

DeFi liquidity deposits and receipt-token exchanges need their own analysis. They can create a disposal where beneficial ownership transfers or the rights received are materially different. Receiving a new token (for example, stETH or an LP token) is evidence to examine, not a conclusive tax rule by itself.

What is NOT a disposal

Not every on-chain transaction triggers CGT. The following are generally not treated as disposals:

• Moving crypto between your own wallets: transferring ETH from Coinbase to MetaMask is not a disposal
• Direct wrapping and unwrapping: ETH ↔ WETH can preserve the same ownership and economic exposure
• Aave supply and withdrawal: fact-specific under CRYPTO61620; beneficial ownership and any receipt token or right received determine whether a disposal occurs

CGT rates: the 2024/25 split year

The Autumn Budget on 30 October 2024 changed Capital Gains Tax rates with immediate effect on the same day. This makes 2024/25 a split year, and the rate that applies to each disposal depends on when it happened.

This means you cannot apply a single CGT rate to the whole year. Every individual disposal must be checked against the 30 October boundary. If you swapped tokens on 15 October, that's 10% or 20%. If you swapped again on 15 November, that's 18% or 24%.

The split is handled through Box 51 on the SA108 form, which requires you to calculate an adjustment for disposals taxed at different rates within the same year. Most crypto tax calculators don't handle this. They apply one rate to the entire year, which is incorrect.

The annual exempt amount: £3,000

The Capital Gains Tax annual exempt amount for 2024/25 is £3,000. This is the amount of net gains you can make in a tax year before CGT applies. It's been cut sharply over the past three years:

CPI indexation of the exempt amount has been abolished, so £3,000 is now the permanent level. Activity that was comfortably below the threshold two years ago may now be taxable.

The exempt amount applies to your total capital gains from all sources, not just crypto. If you also sold shares or property in the year, those gains count too.

HMRC's three matching rules

When you dispose of a token, you need to determine the cost basis: what you originally paid for those specific tokens. HMRC doesn't let you choose which purchase to match against. There's a strict priority order defined in TCGA 1992 and clarified in HMRC's Cryptoassets Manual (CRYPTO22200):

1. Same-day rule: if you acquired and disposed of the same token on the same day, those are matched first. This prevents artificial loss creation through intra-day wash sales.
2. 30-day Bed & Breakfast rule: if you disposed of a token and reacquired the same token within 30 days after the disposal, the disposal is matched against that reacquisition. The 30-day window runs from the day after the disposal.
3. Section 104 pool: everything else goes into a shared pool for that token type, with an average cost basis. Every acquisition adds to the pool (increasing the total cost and units); every disposal draws from it proportionally.

Each token type (ETH, USDC, UNI, etc.) has its own Section 104 pool. NFTs are not pooled. Each NFT is treated as a separate asset. For a detailed walkthrough of these rules, see same-day and B&B rules explained.

Example: how matching works in practice

Allowable costs

HMRC allows you to deduct certain costs from your disposal proceeds when calculating your gain. These are defined in CRYPTO22150:

What you can deduct

• Acquisition cost: the GBP value of the tokens when you bought or received them
• Gas fees and network transaction fees: both on the acquisition and disposal transaction
• Exchange trading fees: on swaps, HMRC expects these to be split 50/50 between the acquisition and disposal sides
• Professional valuation costs: if you paid someone to value an obscure token at the time of a transaction

What you cannot deduct

• Mining hardware and electricity: these are trading expenses, not allowable costs for CGT. They may be deductible if you're classified as a trader (rare for individuals)
• Fiat deposit and withdrawal fees: charges for moving GBP in/out of an exchange are not part of the acquisition or disposal
• Tax software subscriptions: not an allowable cost, though you may be able to claim this as a business expense if you're a sole trader

Crypto income: staking, airdrops, and DeFi

Not all crypto tax is Capital Gains Tax. Some crypto activity generates income, which is taxed at your income tax rate (20%, 40%, or 45%) and reported on the main SA100 return, not SA108.

Staking rewards

Rewards received from staking (whether on-chain like Lido or through an exchange like Coinbase) are treated as miscellaneous income and taxed at their fair market value (FMV) on the date you receive them. When you later dispose of those tokens, CGT applies with a cost basis equal to the FMV at receipt.

Mining income

Mining rewards are treated the same as staking: miscellaneous income at FMV on receipt. HMRC considers most individual miners to be receiving miscellaneous income, not trading income. The £1,000 trading and miscellaneous income allowance may apply if your total miscellaneous income is below this threshold.

Airdrops

The tax treatment depends on whether you did anything to receive them:

• Airdrops without conditions (you didn't do anything to receive them), not subject to Income Tax on receipt (CRYPTO21250). You only pay CGT when you later dispose of the tokens. Because there was no income event, the cost basis is nil, meaning the entire disposal value is a gain.
• Airdrops with conditions (e.g. retweeting, holding a minimum balance, providing feedback), treated as miscellaneous income at FMV on receipt, then CGT on later disposal.

DeFi income

Liquidity provider fees earned on protocols like Uniswap V3 are treated as miscellaneous income. On V2, fees are automatically reinvested into the pool, making them harder to isolate, but they're still income in principle. Interest earned from DeFi lending protocols is generally also income. For the full breakdown, see DeFi income vs capital gains.

The new SA108 cryptoassets section

For 2024/25, HMRC has added a dedicated cryptoassets section to the SA108 Capital Gains Summary form. This is the first time crypto has its own boxes. Previously, crypto gains were reported under "other assets."

The new section has eight boxes:

Boxes 13.7 and 13.8 will be zero for most people. They apply to a real-time reporting service that very few taxpayers use.

Box 51: the split-year adjustment

Because CGT rates changed on 30 October 2024, Box 51 on the SA108 requires you to calculate an adjustment that accounts for disposals taxed at different rates within the same year. You need to separate your gains into two groups:

• Gains from disposals before 30 October 2024 (taxed at 10%/20%)
• Gains from disposals on or after 30 October 2024 (taxed at 18%/24%)

The Box 51 figure is the difference between the tax calculated at the new rates on all gains and the tax that should actually apply when each disposal uses its correct rate.

Capital losses: how to use them

If your disposals result in a loss, you can use that loss to reduce your CGT bill, but the rules are specific:

• Same-year losses are deducted first. This offset is mandatory and can reduce your net gain below the annual exempt amount
• Carried-forward losses from previous years can only reduce your gains down to the annual exempt amount, not below it. You cannot use carried-forward losses to create an overall loss position
• You must claim losses within 4 years of the end of the tax year in which the loss arose (e.g. 2024/25 losses must be claimed by 5 April 2029)

For the full mechanics of how losses work and when to claim them, see crypto losses and tax relief.

DeFi-specific considerations

DeFi activity is where classification needs more context. Here's a summary of the key areas, and each deserves its own guide (and we're publishing those separately):

Liquidity provider positions

Liquidity additions and removals can create disposals where beneficial ownership transfers or the LP rights are materially different. ChainTax currently applies a disclosed disposal-and-reacquisition treatment to supported LP activity for this tax year, but the result is fact-specific under CRYPTO61620. Fee returns are analysed separately for income treatment. Read the full guide to LP tax treatment →

Liquid staking (Lido, Rocket Pool)

Depositing ETH for stETH or rETH requires the rights and beneficial ownership to be examined; receiving a different token is evidence, not a conclusive rule by itself. Returns accrued through the liquid-staking token also need their nature and timing checked. A later sale or swap of the staked token is considered separately for CGT. Read the full guide to staking tax treatment →

Lending (Aave, Compound)

Under HMRC CRYPTO61620, supplying tokens can be a disposal if beneficial ownership transfers, and receiving a claim or receipt token can amount to a token exchange. Draft No Gain / No Loss rules published on 13 July 2026 propose different treatment for qualifying lending, borrowing, and AMM arrangements from 6 April 2027. They are not yet enacted, so they do not replace the rules that applied in 2024/25.

Wrapping tokens

ChainTax carries basis across a direct ETH to WETH wrap where the evidence preserves the same beneficial owner and economic exposure. Do not extend that conclusion automatically to receipt or liquid-staking wrappers with different rights.

Penalties for late or incorrect filing

HMRC's penalty regime for Self Assessment is tiered and cumulative:

Late filing

• £100 immediately: applies even if you owe no tax
• £10 per day after 3 months (up to 90 days = £900 maximum)
• 5% of the tax due or £300 (whichever is greater) at 6 months
• A further 5% or £300 at 12 months

Late payment

• 5% surcharge on tax unpaid after 30 days
• A further 5% at 6 months
• A further 5% at 12 months
• Plus daily interest at the Bank of England base rate + 4%

Inaccuracy penalties

Voluntary disclosure before HMRC contacts you significantly reduces penalties. A careless error disclosed voluntarily typically attracts 0–15%, compared to 15–30% if HMRC discovers it. The message is clear: fix it now, before the data-matching catches up. Our CARF 2027 readiness page sets out the reconciliation steps for open tax years.

CARF: why your declared gains matter more than ever

The Crypto-Asset Reporting Framework (CARF) came into force in the UK on 1 January 2026. Around 50 UK crypto platforms are now collecting user transaction data: names, addresses, National Insurance numbers, and full transaction summaries, ready to report directly to HMRC.

The first reports are due to HMRC by 31 May 2027, covering the 2026 calendar year. But HMRC already holds historical exchange data collected under existing Finance Act powers. CARF simply makes the reporting automatic, comprehensive, and standardised across 48 countries.

Because platforms only began collecting CARF data on 1 January 2026 and the first reports are due by 31 May 2027, your 2026/27 return (due 31 January 2028) will be the first one HMRC can systematically cross-reference against the full, standardised CARF feed. That said, HMRC already cross-checks earlier years (including 2024/25) using its existing powers: exchange data requests, blockchain analytics, and the 100,000-letter nudge campaign. If your declared gains for any open year don't match what your exchange holds, expect questions.

Step-by-step: filing your 2024/25 crypto tax return

1. Gather your transaction history. Export data from every exchange you've used. For DeFi activity, you need on-chain data, because exchange CSVs won't capture swaps, LP positions, or staking done directly on-chain.
2. Identify every disposal. Remember: crypto-to-crypto swaps, LP deposits, and spending are all disposals. If you only count sell-to-GBP, your return is incomplete.
3. Apply HMRC's matching rules. Same-day, then 30-day B&B, then Section 104 pool. A simple "bought at X, sold at Y" calculation is not sufficient.
4. Calculate gains using the correct CGT rate. Check each disposal against the 30 October 2024 boundary. Use the old rates (10%/20%) before, new rates (18%/24%) on or after.
5. Separate income from capital gains. Staking rewards and LP fees are miscellaneous income on SA100. Disposals go on SA108 in the new cryptoassets section (boxes 13.1–13.8).
6. Deduct losses and the annual exempt amount. Same-year losses offset first (mandatory). Then the £3,000 AEA. Then carried-forward losses (only down to AEA level).
7. Complete Box 51 if you have disposals in both periods. This split-year adjustment is easy to omit.
8. File online by the deadline. For 2025/26 that's 31 January 2027; pay any tax owed by the same date. The 2024/25 online deadline (31 January 2026) has passed. If you still need to file that year, submit a late return as soon as you can. If you can't pay in full, HMRC offers Time to Pay arrangements, but you must contact them rather than ignore it.