When preparing Self Assessment, one crypto portfolio can create capital gains, taxable income, and allowable losses. SA100 is your main return. SA108 summarises reportable gains and losses from crypto disposals. Staking rewards usually go through the relevant SA100 income sections.
The real risk is not the form itself. It is treating a token swap as harmless because no pounds reached your bank.
Put a crypto amount on SA108 when a disposal creates a reportable capital gain or loss. Sales, swaps, gifts, and spending crypto can all be disposals. Put taxable crypto income in the relevant SA100 income sections.
Keep transfers between your own wallets, coins still held, and unrealised price rises in your records only. An unrealised rise means the value has increased, but you have not sold or swapped the asset.
A wallet transfer is usually like moving cash between your own coat pockets. You still own the same asset, so there is normally no tax event.
Transaction-by-transaction decision matrix
| Crypto activity | Tax event | Return area | Evidence to retain |
|---|
| Sell Bitcoin for GBP | CGT disposal | SA108, if reportable | Date, GBP proceeds, fees, pooled cost |
| Swap Bitcoin for Ether | CGT disposal | SA108, if reportable | GBP value at swap time, fees, cost rules |
| Receive normal staking rewards | Usually income on receipt | Relevant SA100 income pages | Receipt date, token quantity, GBP value |
| Sell rewarded tokens later | Potential CGT disposal | SA108, if reportable | Income value on receipt, sale value, fees |
| Move coins between own wallets | No disposal in normal cases | Neither yet | Wallet addresses and transaction ID |
| Hold coins while price rises | No disposal | Neither yet | Acquisition record and holding evidence |
A token can affect income tax first and CGT later. A £600 staking reward may be income when received. A later sale for £850 can create a capital gain, subject to pooling rules.
For the 2025/26 tax year, ending 5 April 2026: Paper Self Assessment returns normally need to reach HMRC by 31 October 2026. Online returns normally have until 31 January 2027. Check current GOV.UK deadlines if HMRC gives you a different date.
Why swaps and rewards split between CGT and income
Crypto swaps are usually capital disposals. Staking rewards may be taxable income when received. The key questions are what you gave up, what you received, and why.
Swapping Bitcoin for Ether counts as disposing of Bitcoin. Your proceeds are normally the pound sterling market value of the Ether received. Sometimes the Bitcoin value gives a clearer figure.
No cash needs to arrive in your bank account.
Staking rewards are usually income at their sterling value on receipt. That value normally becomes their starting cost for later CGT. Airdrops need separate review because the reason for receipt matters.
The most common error here is reporting every token receipt as a capital gain. That can miss income tax due when the reward first reached your wallet.
Build your crypto computation before the return
Build your calculation before entering totals. Use a working sheet that shows every income figure, gain, and loss in pounds sterling.
Your return contains summary figures. Your computation is the working behind them, like the receipts behind a household expense total.
Apply the section 104 pool correctly
A Section 104 holding combines the cost of identical cryptoassets. You cannot choose the purchase price that gives the best tax result.
Apply the same-day rule first. Then match purchases made within the following 30 days. Use the Section 104 pool for any remaining disposal.
These matching rules can change a gain sharply.
Keep this evidence for six years
HMRC generally expects Self Assessment records for at least five years after the 31 January filing deadline. Keeping crypto records for six years gives a safer margin.
- Keep the transaction date, time, asset disposed of, asset received, and transaction ID.
- Keep the GBP market value at each tax event and the price source used.
- Keep exchange fees, network fees, deposits, withdrawals, and wallet records.
- Keep same-day matches, 30-day matches, and the closing Section 104 pool cost.
- Keep income values, allowable losses, and documents supporting each amount.
One token can create two tax moments
1. Reward received
Record its GBP value as income.
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2. Token sold or swapped
Compare proceeds with its recorded cost.
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3. Return entries
Income may go on SA100. Gains may go on SA108.
Good records make the form entry much easier. The next section shows where those final totals normally go.
Put totals in the right online or paper pages
Online filers answer HMRC questions to open income and capital gains sections. Paper filers may need SA108 and the right income supplementary pages.
SA100 is the core return. SA108 is the Capital Gains Summary. Both forms rely on the detailed calculation you keep outside the return.
Online filing versus paper SA108
Online filing opens sections through HMRC questions. Paper filers must select supplementary sheets themselves. Keep the detailed computation behind every summary total.
There is no dedicated cryptoassets box on the paper SA108. Use the relevant gains, losses, and losses-brought-forward entries. Keep a separate computation listing each sale, swap, and allowable loss.
The main SA100 has no universal crypto-income field.
Normal staking income outside a trade will often fit the relevant other income route. Trading activity may need self-employment pages. Check the forms and notes for your filed year before submission.
Worked 2025/26 annual example
Assume Priya, an England taxpayer, made these transactions between 6 April 2025 and 5 April 2026. The figures already reflect same-day, 30-day, and Section 104 rules.
| Event | Tax treatment | Amount entering calculation | Return destination |
|---|
| Bitcoin sale for GBP | Capital gain | £4,800 gain | SA108 |
| Ether swapped for Solana | Capital gain | £1,700 gain | SA108 |
| Staking rewards received | Income on receipt | £900 income | Relevant SA100 income pages |
| Unconnected airdrop received | No income assumed | £0 now | Keep records |
| Loss on token disposal | Allowable capital loss | £1,200 loss | SA108 and loss claim |
Priya has £6,500 gains and a £1,200 loss. Her net gains are £5,300. After the £3,000 annual exempt amount, £2,300 may be taxable. Her £900 staking income is considered separately.
For 2025/26, put staking income and disposal gains into separate calculations. Apply the £3,000 annual exempt amount only to net capital gains. Do not reduce staking income by that allowance. A token reward can create income on receipt and CGT on disposal. This split is the safest way to avoid mixing two different taxes.
A separate, fuller calculation shows why separate totals matter.
- A Bitcoin sale for £10,000 has an allowable pooled cost of £6,100. This creates a £3,900 gain.
- A Bitcoin to Ether swap is worth £4,000. Its matched cost is £2,900, creating a £1,100 gain.
- The swap is taxable even though no sterling is received. Staking rewards worth £600 are income on receipt.
- Reward tokens later sold for £850 create a £250 gain before asset pooling rules apply.
- An unconnected airdrop still held creates no disposal on these facts. Another disposal creates a £1,200 allowable loss.
- SA108 totals are £5,250 gains less £1,200 losses. Net gains are £4,050.
- After the £3,000 annual exempt amount, £1,050 may be taxable. The SA100 income total is £600.
Do not lose a crypto loss or misclassify income
Calculate, prove, and claim an allowable capital loss within the relevant time limit. Otherwise HMRC may not recognise it against future gains.
A capital loss is like a receipt for a bad investment outcome. It can reduce gains, but only if you keep proof and make the claim.
A nil tax bill can still need reporting
A gain covered by the £3,000 annual exempt amount can still need reporting. Total disposal proceeds and HMRC requirements can matter even when no CGT is due.
For 2025/26, reporting may be required even when your final crypto CGT bill is nil. Report if gains before the allowance exceed £3,000. Report if disposal proceeds exceed £50,000, if claiming losses, or if HMRC asks.
“Proceeds” means the sterling value from all crypto disposals. It includes sales, gifts, crypto spending, and token swaps. It does not mean only cash withdrawn to your bank.
Cases outside this simple split
Airdrops, mining, and staking depend on why you received tokens. Services provided and trading activity can also change the answer. Putting every reward on SA108 can understate income tax.
A common case involves a taxpayer who reports staking only as a later gain. The income value on receipt is then missing. That also gives the later tokens the wrong CGT cost.
This guide does not replace advice for complex DeFi, lending, liquidity pools, wrapped tokens, employment tokens, professional trading, limited companies, non-UK residence, or transitional tax rules. These facts may not fit a simple SA100 versus SA108 split. Seek UK tax advice before filing if any apply.
For a 2025/26 online return filed by 31 January 2027, you can normally amend it by 31 January 2028. After that, contact HMRC and explain the correction.
These exceptions matter most before you press submit. The questions below cover the usual points for simpler portfolios.
Frequently asked questions
Do I put crypto on SA100 or SA108?
Put crypto income on relevant SA100 supplementary pages. Put reportable gains or losses from disposals on SA108. Bitcoin sales, token swaps, and crypto spending can be disposals. Ordinary staking rewards are usually income on receipt.
Is swapping one cryptocurrency for another a taxable disposal?
Yes. A crypto-to-crypto swap is usually a CGT disposal at its pound sterling market value. It can create a gain or loss even when you receive no cash.
Do I need to report crypto losses to HMRC?
Claim an allowable crypto loss if you want it available against gains. This includes future gains. The usual claim deadline is four years after the tax year of the loss.
No universal crypto-income box exists on the main SA100 return. HMRC may direct income to different supplementary pages. The route depends on whether it is trading income, miscellaneous income, or another category.
File from a checked computation, not an app total
Classify each event, calculate in GBP, and enter income and capital totals separately. Keep the full working paper even if the online return asks only for summary figures.
An app total can be useful, but it is not proof that HMRC rules were applied correctly. Check swaps, reward values, fees, and matching rules before you file.
The essentials:- SA100 is the main return, while SA108 summarises gains and losses from reportable crypto disposals.
- Crypto-to-crypto swaps can create CGT before any pounds reach your bank.
- Staking rewards may be income first, then create a later CGT calculation.
- Apply same-day, 30-day, and Section 104 pooling rules before entering capital totals.
- Check current HMRC forms, notes, and deadlines for the tax year you are filing.
Review HMRC’s current Self Assessment guidance before entering final figures. Prepare your SA108 computation working sheet first.
Further reading
If you want to learn more about this topic, these sources may interest you:
