Part 1
Quick Assessment for Accountants
This first section is the practical bit. Use it to decide whether the client has anything to report.
The Three Reporting Triggers
A client may need to report crypto activity if any one of these applies.
Capital gains exceed the annual exempt amount
If your client's total capital gains for the year exceed the £3,000 annual exempt amount, the gains must be reported on SA108.
Total disposal proceeds exceed £50,000
Even where no Capital Gains Tax is due, reporting is still required if total disposal proceeds for the year exceed £50,000.
Crypto income has been received
If the client received staking rewards, airdrops, mining income, or payment in crypto, there may be an income reporting issue even where gains are low.
Crypto losses may be worth reporting
Reporting losses is not always mandatory, but it is often sensible. If a client has made allowable crypto losses, they can usually be claimed and carried forward to offset future capital gains.
In practice, a client who says they “lost money on crypto” should not automatically be treated as outside scope. The losses may still have tax value.
Interactive triage quiz
Work through this in under two minutes. Then use the full questionnaire below if you need more detail.
Has the client sold, swapped, spent, or gifted crypto?
Swapping one crypto for another still counts as activity worth checking.
Has the client used personal wallets as well as exchange accounts?
A wallet usually means there may be activity outside exchange CSV exports.
Has the client used crypto apps, DeFi tools, bridges, or blockchain-based services?
These are the cases where people often say “I didn’t sell anything” but still need review.
Has the client received staking rewards, airdrops, mining income, or payment in crypto?
These can create an income reporting issue even where gains are modest.
Are records spread across multiple exchanges, wallets, or years?
Complex record keeping is often the practical reason specialist help is needed.
Are you unsure whether any of the activity creates a reporting obligation?
If the answer is not obvious, the case is usually no longer a standard one.
Assessment
Start with the questions below
This is a triage tool. A single yes does not automatically mean a tax charge, but it usually means the client should not be treated as a simple “no crypto issue” case.
Answers completed: 0 of 6
Part 2
Detailed Practitioner Reference
Use this section when you need the underlying rationale, the actual reporting triggers, or a more formal checklist to build into your client process.
Why This Matters Now
Three developments have changed the compliance landscape for crypto in the UK.
CARF is live
The Cryptoasset Reporting Framework came into force on 1 January 2026. UK crypto exchanges and service providers are now legally required to collect and report user data — including names, tax residency, National Insurance numbers, and full transaction records — to HMRC. The first reports are due by 31 May 2027, covering calendar year 2026. From that point, HMRC will be able to cross-reference exchange data directly against Self Assessment returns.
SA108 has a dedicated cryptoassets section
For 2025–26 returns, crypto disposals are reported in their own section of SA108 (boxes 13.1–13.8), separate from shares, property, and other assets. This is not cosmetic. It signals that HMRC expects crypto to be identified and reported explicitly, not bundled into “other assets”.
HMRC is actively pursuing non-compliance
HMRC sent over 65,000 nudge letters to suspected crypto non-compliers during 2024–25. It has obtained data from exchanges including Coinbase under existing information powers, and it operates a dedicated Cryptoasset Disclosure Facility for voluntary corrections. The enforcement posture is clear: clients who have not disclosed are increasingly likely to be identified.
For any practice handling personal tax returns, the question is no longer whether your clients hold crypto. It is whether you are asking.
Most On-Chain Actions Create Taxable Events
On-chain means activity carried out directly through wallets, blockchains, or crypto apps, not just selling coins on a normal exchange account.
This matters because clients often say they “didn't sell anything” when what they really mean is they never withdrew cash to their bank. That does not rule out a reporting obligation.
Swapping crypto
Changing one token into another can count, even if the client stayed entirely within crypto.
Spending or gifting
Paying with crypto or gifting it away can matter, even if no cash was received.
Using crypto apps
Moving assets through wallets, bridges, or crypto apps can change what the client holds and may need review.
Technical examples
If you need the jargon-heavy version, these are the kinds of actions that often create work in practice.
See technical examples
- Wrapping tokens, such as ETH to WETH or BTC to WBTC
- Providing liquidity to DeFi pools or receiving LP tokens
- Gas fees paid in crypto
- Bridging assets between blockchains
Client Screening Checklist
This is the laid-out version of the questionnaire. It is intended for year-end packs, onboarding forms, or internal review notes.
The shorter quiz above is for triage. This version is for process.
Ownership and accounts
- Do you hold any cryptocurrency or digital assets?
- Do you hold crypto in any personal wallets, whether hardware or software?
- Have you used any decentralised exchanges or DeFi platforms?
Disposals and transactions
- Have you sold any crypto for pounds or another currency?
- Have you swapped one cryptocurrency for another?
- Have you used crypto to pay for anything?
- Have you given crypto to anyone other than your spouse or civil partner?
On-chain activity
- Have you moved assets through bridges, DeFi apps, or lending protocols?
- Have you wrapped or unwrapped any tokens?
- Have you provided liquidity to any pool or protocol?
- Have you interacted with any staking, borrowing, or yield products?
Income
- Have you received any staking rewards?
- Have you received any airdropped tokens?
- Have you been paid in crypto for any work or services?
- Have you received any mining rewards?
Record keeping
- Can you provide CSV exports or API access for each exchange account?
- Can you provide wallet addresses for any personal wallets?
- Do you have records of your original purchase prices and dates?
The SA108 Cryptoassets Section (Boxes 13.1–13.8)
For 2025–26 returns, SA108 includes a dedicated cryptoassets section. This sits on page CG1 of the form, between the residential property and the general “Other property, assets and gains” section.
| Box | Description |
|---|---|
| 13.1 | Number of disposals |
| 13.2 | Disposal proceeds |
| 13.3 | Allowable costs, including purchase price |
| 13.4 | Gains in the year, before losses |
| 13.5 | Losses in the year |
| 13.6 | Claim or election code |
| 13.7 | Total gains or losses reported via Real Time Transaction returns |
| 13.8 | Tax on gains in box 13.7 already paid |
- Crypto disposals should no longer go in boxes 14–22
- Previously, crypto was reported under “Other property, assets and gains”. For 2025–26, it has its own section.
- Figures are aggregates
- HMRC expects year totals for disposals, proceeds, allowable costs, gains, and losses. Individual transactions must still be supported by computations.
- Computations must be enclosed
- For crypto, that means a full schedule of disposals with dates, assets, proceeds, costs, and gain or loss per transaction, applying section 104 pooling and the matching rules.
Crypto Income: SA100 Box 17
Where a client receives crypto as income, the pound sterling value at the date of receipt is taxable as income. This is normally reported on SA100 under box 17, with related expenses in box 18 where appropriate.
- The Personal Savings Allowance does not normally apply.
- National Insurance is not normally due unless the activity amounts to a trade.
- The £1,000 trading allowance may cover small miscellaneous amounts in the right circumstances.
Double taxation is expected
Once crypto is received as income, its value at receipt becomes the cost basis for future CGT purposes. If the client later sells or swaps those tokens, any increase in value is a separate capital gain.
How BlockBooks Works With Practices
If your client has reportable crypto activity, the reconciliation work is specialist work. It requires tooling and expertise that most general practices do not carry in-house.
BlockBooks exists to handle that layer. We work directly with accounting practices on a referral or white-label basis.
- 1
You refer or onboard the client
- 2
We reconcile all exchange and on-chain activity
- 3
We deliver HMRC-ready working papers
SA108 Capital Gains summary, income schedule, and a full audit trail.
- 4
You retain the client relationship and file the return
Pricing is agreed upfront based on exchanges, wallets, and the complexity of the activity. Every reconciliation is completed by a Big Four-trained accountant with specialist crypto tax experience.
Ready to discuss a partnership?
Let's talk about how BlockBooks can support your practice with crypto tax reconciliations.
This guide explains HMRC's rules as they apply to the 2025–26 tax year. It is not personalised tax advice. For complex situations, specialist review is recommended.