What is the Self Assessment Tax Return?
The Self Assessment Tax Return is the official process for UK taxpayers to declare all their income and capital gains to HMRC, including those from cryptocurrencies. If you have earned income (like staking or mining rewards) or made profits from selling or exchanging crypto, you are required to report these using SA100 and SA108 forms.
ℹ️ Declaration deadline
The deadline for submitting your tax return is 31 January following the end of the tax year (for example, for the 2023–2024 tax year, the deadline is 31 January 2025). This means that your 2025 tax return covers all transactions and income earned between 6 April 2024 and 5 April 2025.
The CryptoBooks precompiled Report
The report you receive from CryptoBooks is designed to help you fill out your tax return correctly, providing both pre-calculated figures and clear instructions on where to enter them in the official HMRC forms.
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The report is divided into two main sections:
Crypto income (Other Taxable Income – SA100)
Capital gains and losses from crypto (Capital Gains – SA108)
The crypto data to calculate CGT adjustment (only for 2024-25)
Each section of the CryptoBooks report includes a detailed guide on how to complete the corresponding part of your tax return. You’ll also find attached a complete list of your taxable transactions, which you can either submit with your tax declaration or keep for your records in case of a tax audit.
Crypto Income - SA100
Not all crypto earnings are capital gains. Some, such as rewards from staking, mining, airdrops, or exchange bonuses, are considered “other income” and must be declared in the SA100 form.
If you want more information about what kind of transactions generate crypto income, you can check out our tax guide.
How to declare crypto income
in box 17 enter the total value (in GBP) of crypto received as rewards during the tax year, calculated at the time of receipt
in box 21 write a brief description of the income source, for example: “Crypto income from non-trading activities: mining, staking, etc.
Practical example
If you received 0.1 ETH as a staking reward and it was worth £300 at the time of receipt, you must enter £300 as income in Box 17.
Your CryptoBooks report will provide both the total amount you need to declare and a detailed breakdown of each transaction, which you can attach to your tax return.
Capital gains and losses - SA108
Whenever you sell, exchange, use, or give away your cryptocurrencies, you trigger a capital gain or loss that needs to be reported on the SA108 form. If your total gains for the year exceed the annual tax-free allowance, or if you want to claim losses to offset other gains, you are required to declare these amounts in your tax return.
If you want more information about what kind of transactions generate crypto capital gain/loss, you can check out our tax guide.
How to declare crypto capital gain/loss
Follow these steps to correctly declare capital gains:
in the section "What makes up your tax return?" of the SA100 form, tick Yes to the question about capital gains (this is usually the 7th option on the form). This notifies HMRC that you have capital gains or losses to declare
in box 13.1 of SA108, enter the total number of disposal transactions you made during the tax year, a disposal
in box 13.2, indicate the combined value in GBP that you received from all your crypto sales or swaps during the year for each transaction, using the value of the crypto at the time you sold or swapped it, then add up all these amounts
box 13.3 is where you report the total amount you originally paid to acquire the crypto assets you disposed of, including any transaction fees or costs related to buying or selling. These allowable costs help reduce your taxable gain
for box 13.4, calculate and enter the total amount of gains you made from all your disposal transactions. For each transaction, subtract your allowable costs from the value you received. Add up all the transactions where you made a profit to get your total gains
finally, in box 13.5, include the total amount of losses you realised from your disposals for each transaction where your allowable costs were higher than the value you received. Add up all these losses to report the total
Your CryptoBooks report will provide all the data you need to declare and a detailed breakdown of each transaction, which you can attach to your tax return.
Capital gain adjustment - Update 2024/25
From 30 October 2024, Capital Gains Tax (CGT) rates have changed:
Before this date: 10% (basic rate), 20% (higher rate)
After this date: 18% (basic), 24% (higher)
⚠️ CGT adjustment if you made any capital gain after 30 October 2024
HMRC’s software currently calculates Capital Gains Tax using only the 10% and 18% rates. If you have made any capital gains after 30 October 2024, you must calculate and declare the capital gain adjustment to ensure you pay the correct amount of tax.
To calculate your capital gain adjustment, you can use the tool provided by HRMC at this link.
This adjustment applies to all capital gains, including those from cryptocurrencies, and should be calculated separately and entered in box 51 of the SA108 form. Your CryptoBooks report will provide all the data you need to determine the portion of your crypto gains before and after the rate change.