How to Report Crypto on Your Self Assessment Tax Return
July 14, 20263 min read
Key Takeaways
Crypto capital gains go on SA108 (Capital Gains Tax pages) in Boxes 7-10 and 35-36, with the annual exempt amount of £3,000 for 2025-26.
Crypto income from staking, mining, and airdrops goes on SA100 Box 9 (miscellaneous income) if occasional, or SA103 (self-employment) if you are trading as a business.
You must file if your crypto gains exceed £3,000, your total disposals exceed £50,000, or your crypto income exceeds £1,000 — even if the gain itself is small.
HMRC accepts reasonable estimates when exact figures are unavailable, but keep records of your methodology. Careless errors attract penalties of 0-30% of the tax due.
The online self assessment deadline is 31 January 2027 for the 2025-26 tax year — file and pay by this date to avoid late filing penalties.
Filing crypto on your self assessment return requires the right boxes and calculations. Here’s where everything goes.
Do You Need to File?
Condition
Must File?
Crypto gains over £3,000
Yes
Total disposals over £50,000
Yes (even if gain is under £3K)
Crypto income over £1,000
Yes
Already file self assessment
Yes (add crypto sections)
Gains under £3K and disposals under £50K and no other filing requirement
No
Where to Report Capital Gains
SA108 (Capital Gains Tax) Pages
Box
What to Enter
Box 7
Total chargeable gains from crypto
Box 8
Total allowable losses from crypto
Box 9
Unused losses from previous years
Box 10
Net chargeable gains (Box 7 - Box 8 - Box 9)
Box 35
Annual exempt amount (£3,000 for 2025-26)
Box 36
Taxable gain (Box 10 - Box 35)
Where to Report Crypto Income
Income Type
Section
Box
Staking rewards (occasional)
SA100 (Main return)
Box 9 (Miscellaneous income)
Staking rewards (trading)
SA103 (Self-employment)
Trading income
Mining income (hobby)
SA100
Box 9
Mining income (business)
SA103
Trading income
Airdrops (occasional)
SA100
Box 9
Airdrops (trading)
SA103
Trading income
DeFi lending interest
SA100
Box 9
Self-Employment vs Miscellaneous Income
Factor
Miscellaneous (Box 9)
Self-Employment (SA103)
Frequency
Occasional
Regular, organised
Profit motive
Incidental
Primary activity
Hobby or business
Hobby
Business
Expenses
Not deductible
Deductible
National Insurance
No
Yes
What If You Don’t Have Exact Figures?
Situation
Best Approach
Missing transaction data
Use best estimate, note the method
Lost exchange access
Reconstruct from blockchain data
Incomplete wallet records
Document what you have
Complex DeFi interactions
Use crypto tax software
HMRC accepts reasonable estimates if exact figures are unavailable, but exact records are better.
Penalties for Errors
Error Type
Penalty
Careless error
0-30% of tax due
Deliberate error
20-70% of tax due
Deliberate + concealed
30-100% of tax due
Late filing
£100 + daily penalties
Deadline
Event
Date
Tax year ends
5 April 2026
Online return deadline
31 January 2027
Payment deadline
31 January 2027
Bottom Line
Report crypto capital gains on SA108 (CGT pages). Report crypto income (staking, mining, airdrops) on SA100 Box 9 (miscellaneous) or SA103 (if trading as a business). Use crypto tax software for accuracy. File by 31 January. If you’re unsure about any section, professional advice is worth the cost to avoid penalties.
Getting Your Records in Order
The biggest challenge with crypto self assessment is not the form itself — it is getting accurate figures from fragmented records spread across exchanges, wallets, and DeFi protocols. Start by exporting transaction histories from every exchange you have used. Most major exchanges (Coinbase, Binance, Kraken) allow CSV downloads of your full transaction history.
For wallet transactions, blockchain explorers like Etherscan can fill in the gaps, though reconstructing years of DeFi interactions from on-chain data is time-consuming. Crypto tax software automates most of this by connecting via API or importing CSVs, calculating your cost basis using HMRC’s share pooling rules, and generating a report that maps directly to the self assessment boxes.
If you discover you have unreported crypto gains from previous years, do not wait for HMRC to find out. You can amend a return within 12 months of the filing deadline, or make a disclosure under HMRC’s worldwide disclosure facility. The penalties for voluntary disclosure are typically lower than for errors discovered during an investigation.
Frequently Asked Questions
When must I report crypto on my self assessment?
You must file if your crypto capital gains exceed £3,000 (the CGT annual exempt amount for 2025-26), your total disposals exceed £50,000 even if the gain is under £3,000, or your crypto income exceeds £1,000. If you are already registered for self assessment, you should include crypto sections even if your gains are below these thresholds.
What is the difference between miscellaneous income and self-employment for crypto?
Miscellaneous income (SA100 Box 9) applies when crypto activities are occasional or a hobby — you cannot deduct expenses and do not pay National Insurance. Self-employment (SA103) applies when crypto activities are regular, organised, and profit-oriented — you can deduct expenses but must pay National Insurance. HMRC uses badges of trade to decide which applies.
What happens if I miss the self assessment deadline?
Late filing triggers an immediate £100 penalty, plus daily penalties of £10 per day after three months (up to 90 days). Further penalties apply at six and twelve months. Late payment attracts interest charges. The online filing deadline for the 2025-26 tax year is 31 January 2027.
Can I use crypto tax software to calculate my figures?
Yes, and it is typically more accurate than manual calculations for anyone with more than a handful of transactions. Tools like Koinly, CoinTracker, and TaxScools connect to exchanges and wallets via API or CSV import, calculate cost basis using HMRC-approved methods, and generate reports formatted for self assessment. HMRC accepts software-generated figures as long as the underlying data is accurate.
PP
PaisayehPaisa Editorial Team
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