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Worried about how to calculate Capital Gains Tax when swapping one cryptoasset for another? This guide focuses exclusively on Crypto-to-crypto trades CGT and explains, in plain language and with worked examples, how HMRC treats swaps, how valuation works for probate and inheritance, what executors must do with private keys and wallets, and the exact steps beneficiaries should follow to avoid errors when they receive cryptoassets.
Key takeaways: what to know in 1 minute
- Crypto-to-crypto trades are disposals for HMRC purposes and can trigger Capital Gains Tax. A swap of BTC for ETH is treated the same as selling BTC for GBP then buying ETH.
- Base cost for beneficiaries of inherited crypto is the market value in GBP at the date of death; that value becomes the acquisition cost for future CGT calculations.
- Matching and pooling rules apply: same-day matching, 30-day bed-and-breakfast rule, and Section 104 pooling must be used to compute gains on swaps.
- Fees and gas can be allowable costs and should be added to acquisition or disposal figures where evidence exists.
- Executors must secure keys and obtain probate valuations; disposing or transferring assets before correct valuation and advice can create tax complications.
How crypto-to-crypto trades trigger CGT: HMRC rules and the disposal event
HMRC treats a trade that exchanges one cryptoasset for another as a chargeable disposal. The disposal proceeds are the market value in GBP of the crypto received at the time of the swap. The gain is the difference between that proceeds figure and the seller's allowable costs (the acquisition cost of the crypto being disposed of plus any allowable costs such as platform fees or gas where evidencable).
Core points:
- Disposal events include selling for GBP, swapping one crypto for another, spending crypto for goods or services, and gifting (except certain exempt transfers).
- The proceeds for a swap are the GBP market value of the crypto received at the time of the swap. If an exchange reports only token-to-token amounts, the taxpayer should convert to GBP using a reliable exchange price or recognised aggregator for that timestamp.
- Allowable costs: original purchase price (in GBP), transaction fees, and reasonably attributable costs such as network gas if paid directly and evidenced. These reduce the gain.
Worked example (simple swap):
- Acquisition: 1.00 BTC bought for £6,000 (allowable cost £6,000).
- Disposal: 1.00 BTC swapped for 15.0 ETH on 10 March 2025. Market value of 15.0 ETH at swap time = £20,000 (this is disposal proceeds).
- Gain = £20,000 − £6,000 = £14,000 (subject to CGT, after annual allowance and any other reliefs).
If fees or gas of £200 were incurred at acquisition or disposal and evidenced, those can be added to allowable costs or deducted from proceeds where appropriate.
Sources and further HMRC detail: HMRC: Tax on cryptoassets.
How to value Bitcoin and crypto for probate: date of death valuation explained
For probate and estate valuation purposes, the date of death value in GBP is the key figure. That value is used for both inheritance tax (IHT) valuation and to establish the beneficiary's base cost for future CGT when the asset is inherited.
Valuation guidance:
- Use market value at date of death: pick a time on the date of death (commonly the nearest UTC or a consistent timestamp such as 00:00 GMT) and take a mid-market GBP price from a reputable source. Keep evidence (exchange screenshots, API price history, or third-party valuation reports).
- If assets are illiquid or cross-chain: use the most reliable observable price, explain methodology in probate papers and retain evidence. For tokens with negligible markets, a professional valuer may be necessary.
- Multiple wallets/exchanges: value each holding separately, convert each token holding to GBP at the chosen timestamp.
Practical tip: document the exact data source and timestamp in estate paperwork and keep raw export files from exchanges and wallets to support valuations in case HMRC queries the figures.
Reporting inherited crypto to HMRC: IHT and CGT interplay
Two distinct taxes are relevant when crypto is inherited: Inheritance Tax (IHT) on the estate and Capital Gains Tax (CGT) on later disposals by beneficiaries.
IHT:
- The estate is valued including crypto at date of death for IHT assessments. Executors may need to complete forms such as IHT400 or IHT205 depending on estate complexity.
- If the estate value exceeds thresholds, IHT may be payable and tax clearance and distributions must account for that.
CGT for beneficiaries:
- When a beneficiary inherits crypto, the beneficiary's acquisition cost for CGT equals the market value on the date of death (not the decedent's original cost).
- A later swap by the beneficiary (crypto-to-crypto trade) is a disposal and will be subject to CGT using the beneficiary's acquisition cost. For example, if on date of death 1 BTC = £30,000 and the beneficiary swaps that BTC for other tokens later, the base cost is £30,000.
- If the personal representative (executor) disposes of assets to pay estate liabilities before distribution, the executor is responsible for tax on disposals carried out in that role; disposals by executors are treated for CGT in the usual way but timing and reporting responsibilities differ.
Links for IHT detail: HM Government: Inheritance Tax.
Executors’ duties with private keys and wallets: custody, record-keeping and tax consequences
Executors have a fiduciary duty to preserve estate assets. With crypto this means securing private keys and maintaining complete records. Mismanagement can lead to loss of assets and tax complications.
Key duties and good practice:
- Secure keys immediately: place hardware wallets or seed phrases in secure custody (insured safe deposit or professional custodian). Keep chain-of-custody records.
- Avoid unnecessary disposals: do not swap or move assets without clear reason; each disposal is a taxable event and may require reporting. If assets must be sold to pay liabilities, document the commercial reason and obtain valuations.
- Keep exportable evidence: transaction histories, exchange statements, wallet addresses, and timestamps should be exported and retained. These support valuations and CGT calculations.
- Seek specialist tax input: if the estate includes complex DeFi positions, pooled LP tokens, or assets on multiple chains, obtain professional valuations and tax advice before disposals.
Security and privacy note: follow guidance from the National Cyber Security Centre (NCSC) and the Information Commissioner's Office (ICO) for handling personal data and secure storage.
When completing probate documentation, digital assets including crypto must be declared on the appropriate IHT forms and estate inventories.
Practical steps:
- Identify all holdings: list wallet addresses, exchange accounts, token types and approximate balances at date of death. Use account statements and on-chain data where needed.
- Value each holding: convert token quantities to GBP at the chosen date-of-death timestamp and record the source.
- Attach supporting evidence: exchange exports, wallet snapshots and, where necessary, independent valuation reports.
- Declare in IHT forms: include totals and support documents when submitting IHT400 or IHT205. If unsure which form applies, see HMRC guidance or consult probate practitioners.
Useful HM Government pages: Wills, probate and inheritance.
Selling inherited crypto: tax triggers and valuation dates for swaps
When a beneficiary or executor disposes of inherited crypto, the disposal triggers CGT if there is a gain over the acquisition cost. Specific rules for timing and matching must be applied for crypto-to-crypto trades.
Matching and pooling rules (how HMRC requires disposals to be matched to acquisitions):
- Same-day rule: disposals on the same day are matched to acquisitions on that day first.
- 30-day rule (bed and breakfast): acquisitions made within 30 days after a disposal are treated as matched to that disposal. This prevents superficial loss harvesting in normal securities; HMRC applies analogous logic for crypto disposals.
- Section 104 pooling: after same-day and 30-day matching, remaining holdings of the same asset form a Section 104 pool where allowable costs are averaged.
Valuation date rules for inherited crypto:
- The beneficiary's base cost is the market value at date of death.
- If the executor sells before distribution, the executor's disposal date and valuations determine taxable gain on the estate's tax returns. The ultimate tax position can differ depending on whether distribution occurs before or after disposal.
Worked example (inheritance followed by a swap):
- Date of death: 1 BTC valued at £30,000. This becomes the beneficiary’s base cost.
- Beneficiary swaps 1 BTC for 40,000 USDC on 1 July 2026 when 40,000 USDC = £32,000.
- Gain = £32,000 − £30,000 = £2,000 (less annual CGT allowance). Fees of £50 paid on the swap reduce the gain if evidenced.
Note on stablecoin routes: even if the swap path never touches GBP (e.g. BTC→USDC→ETH all off-rampless), HMRC still expects GBP valuations for proceeds and costs at each disposal moment.
Practical steps for beneficiaries receiving crypto inheritances
- Secure the assets immediately and document custody.
- Obtain and record the market value in GBP at date of death for each token (this is the beneficiary’s acquisition cost).
- Keep transaction histories and fee receipts; include gas costs where directly borne.
- If planning a swap (crypto-to-crypto trade), calculate potential CGT using the date-of-death base cost and matching/pooling rules.
- File a Self Assessment if disposals generate gains beyond the annual allowance or if HMRC requires reporting; keep records for at least 22 months after the tax year end (longer for CGT evidence).
(These steps are general considerations and not personalised tax advice. For decisions affecting tax liabilities consult a regulated tax adviser.)
Table: quick compare, inheritance versus lifetime gift versus executor disposal
| Scenario |
IHT |
CGT base cost |
Notes on swaps |
| Inherited at date of death |
Included in estate valuation; possible IHT |
Market value at date of death (GBP) |
Any later swap is disposal for CGT using date-of-death base cost |
| Lifetime gift before death |
Potentially chargeable transfer; taper relief may apply |
Depends on donor’s original cost (unless deemed market value rules apply) |
Recipient’s base cost may differ; swaps still trigger CGT |
| Executor sells to pay liabilities |
Estate bears IHT based on valuations |
Executor’s disposal brings CGT liability for the estate if gain arises |
Document commercial reason; executor must report where applicable |
Table: indicative summary, specific cases can vary and require professional advice.
Steps for inheriting and disposing of crypto
🔐
Step 1 → Secure keys & confirm ownership
Record wallet addresses, captions and custody location.
📅
Step 2 → Fix date-of-death valuation in GBP
Choose a timestamp and retain price evidence.
🔁
Step 3 → Plan any swap with CGT calculations in mind
Apply matching rules and include fees/gas.
🗂️
Step 4 → Keep records for HMRC reporting
Exchange exports, receipts and valuations for at least several years.
Advantages, risks and common mistakes
Benefits / when to apply ✅
- Beneficiaries can use the date-of-death valuation as a clean base cost for CGT, simplifying later calculations.
- Including gas and fees as allowable costs can reduce taxable gains when properly evidenced.
- Planning swaps with pooling and matching rules in mind can preserve the annual CGT allowance.
Errors to avoid / risks ⚠️
- Failing to evidence date-of-death valuations or using inconsistent price sources.
- Moving assets without documenting commercial need (executors) or without understanding tax triggers.
- Ignoring same-day and 30-day matching rules when calculating gains on quick swaps.
- Treating token-to-token swaps as non-taxable because no fiat changed hands, HMRC treats these as disposals.
Frequently asked questions
Do crypto-to-crypto trades trigger CGT?
Yes. HMRC treats a trade exchanging one cryptoasset for another as a disposal; the proceeds equal the GBP market value of the crypto received at the time of the trade.
How is base cost calculated for inherited crypto?
The base cost for a beneficiary is the market value in GBP at the date of death; this figure becomes the acquisition cost for future CGT calculations.
Can gas and fees be included as allowable costs?
Where fees or gas are evidenced and directly attributable to acquisition or disposal, they can be treated as allowable costs and included in calculations to reduce gains.
What are same-day and 30-day matching rules?
HMRC requires disposals to be matched to acquisitions per: same-day first, then acquisitions within 30 days, then Section 104 pooling. These rules affect which acquisition cost is used when computing gains.
Should executors sell crypto before probate is granted?
Executors should not dispose of assets without reason. If sale is needed to pay liabilities, document rationale and valuations; otherwise obtain probate and follow distribution instructions to beneficiaries.
How long should records be kept?
Records supporting CGT and inheritance valuations should be kept for several years—CGT records for at least 22 months after the tax year end, and longer if HMRC enquiries are possible. Longer retention is prudent for complex crypto positions.
Next steps
- Secure and document all wallets and exchange accounts; export transaction histories and record timestamps and price sources.
- Fix GBP valuations at date of death for inherited tokens; save screenshot or API output showing the price and timestamp.
- Before any swap, run a simple CGT calculation applying same-day, 30-day and pooling rules and include evidence of fees/gas. If amounts are significant, consult a regulated tax professional.
