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

The 2024/25 tax year needs particular care: 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. From 1 January 2026, reporting cryptoasset service providers began collecting reportable data 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. Use it to organise the rules, records and questions that need checking before you prepare or amend a return.

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) includes the following disposals, for which you calculate a gain or loss:

• 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.

Transfers and DeFi: check beneficial ownership

A transaction label alone does not establish the tax treatment. Check ownership of the asset and the rights given up or received:

• Moving crypto between your own wallets: moving the same asset while retaining beneficial ownership throughout is not a disposal under CRYPTO22100
• Direct wrapping and unwrapping: ChainTax carries basis for supported ETH ↔ WETH activity where evidence preserves the same beneficial owner and asset rights; this is not a blanket exemption for wrappers
• Aave supply and withdrawal: can involve a disposal; check the contract terms, beneficial ownership and any receipt token or right received under CRYPTO61620

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. When reviewing your crypto tax calculation, check the disposal dates and rates instead of applying one rate to the whole year.

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 amount paid for the asset, or the relevant value already charged to Income Tax where that rule applies; receiving a token does not automatically give it a market-value cost basis
• Gas fees and network transaction fees: where they qualify as costs of acquisition or disposal; check the transaction and allocate the fee without deducting it twice
• Exchange trading fees: allocate swap fees on a just and reasonable basis. HMRC accepts an equal split between the acquired and disposed assets in these circumstances; other approaches are considered case by case
• 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

For consensus staking that does not amount to a trade, HMRC treats the GBP value of awarded tokens at receipt as miscellaneous income. A later disposal can create a capital gain or loss, with the value already taxed as income taken into account. Liquid-staking tokens and DeFi returns need their own ownership, rights and return analysis; do not assume every increase in a receipt token is a new income receipt. See HMRC CRYPTO21200 on staking.

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:

• Receipts without doing anything in return: Income Tax may not apply when the airdrop is not related to a service or other conditions and is not part of a cryptoasset trade or business. A later disposal can still create a chargeable gain; check any allowable acquisition and disposal costs.
• Receipts in return for, or in expectation of, a service: taxable as miscellaneous income or trade receipts. Review the actual eligibility terms and facts; a claim transaction or token-holding requirement alone does not settle the Income Tax treatment.

Source: HMRC CRYPTO21250 on airdrops.

DeFi income

DeFi returns can have the nature of income or capital. HMRC asks you to examine how the arrangement is structured: whether a return rewards a service or reflects growth in an asset, whether it was agreed in advance, and how and when it is realised. No single factor decides the result. Do not automatically treat growth in an LP token as a separate income receipt. Read HMRC CRYPTO61214 on the nature of DeFi returns and the worked explanations in 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 or capital treatment under CRYPTO61214. 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 asset rights. 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 interest at HMRC's applicable late-payment rate

Inaccuracy penalties

HMRC's overview gives these standard ranges as a percentage of the extra tax due from correcting an inaccuracy. Offshore cases can have higher penalties; the applicable rules depend on the facts.

An inaccuracy penalty depends on the facts, including the behaviour involved and whether a disclosure is prompted or unprompted. Its timing and quality can affect the reduction available; coming forward does not guarantee a particular penalty. Assessment time limits are separate from penalty percentages and need their own review. See HMRC's penalties overview and Self Assessment late-filing and payment penalties. Our CARF 2027 readiness page sets out the reconciliation steps for open tax years.

CARF: reconcile records for the correct tax year

The Crypto-Asset Reporting Framework (CARF) came into force in the UK on 1 January 2026. Reporting cryptoasset service providers collect reportable customer and transaction information. This is a reporting framework, not a change to how your 2024/25 gains are calculated.

The first reports are due to HMRC by 31 May 2027, covering the 2026 calendar year. Providers collecting this information does not mean their first CARF reports have already been filed. HMRC may also hold historical exchange information obtained through other powers.

A calendar-year provider report and a UK tax-year return cover different periods. Reconcile the underlying transactions, transfers, costs and income for each relevant tax year rather than expecting the totals to match directly. A difference can have several explanations; it does not by itself establish an error or an enquiry.

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. Check sales, crypto-to-crypto exchanges and spending, as well as DeFi deposits where beneficial ownership or asset rights change. Counting only sales to GBP can miss other disposals.
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. Establish whether a receipt is taxable income or a capital return before assigning it to a return section. Non-trading miscellaneous income and capital disposals have separate reporting requirements; chargeable crypto disposals use the SA108 cryptoassets section.
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.