Coinbase-Only Crypto Tax UK: The Simple Path

A lot of UK crypto users only ever used Coinbase. If that's you, filing your Self Assessment is far simpler than the mess most guides describe. Here's the exact process for the 2026/27 tax year.

Step 1: Export your Coinbase transaction history

In the Coinbase app or web dashboard: Profile → Reports → Transaction history → Generate report → All time (or the specific tax year), CSV format. The file that lands includes every buy, sell, swap, staking payout, learn-and-earn reward, and any received/sent transfer.

For 2026/27, cover 6 April 2026 through 5 April 2027. You'll also need earlier tax years if you've never filed crypto before and any prior activity was disposed within the six-year window — HMRC can go back further under discovery assessment if under-reporting is deliberate.

Step 2: Understand what's taxable

Only three categories on the CSV matter for UK Capital Gains Tax:

- **Sell (crypto → GBP)** — disposal, taxable gain or loss - **Convert / Swap (crypto → crypto)** — disposal of the outgoing token at market value of the incoming, taxable gain or loss - **Send (crypto → external wallet address)** — disposal only if the destination is someone else's wallet; wallet-to-wallet moves between accounts you control aren't disposals

**Not taxable events:**

- **Buy (GBP → crypto)** — acquisition, no immediate tax; just adds to your cost basis pool - **Receive (external wallet → your Coinbase)** — same, an acquisition - **Coinbase-to-Coinbase internal transfers** — non-taxable

**Income, not CGT:**

- **Staking rewards** — Income Tax at the GBP value on the day received. Later disposal of those tokens is a separate CGT event. - **Learn & Earn** — same as staking, income at receipt. - **Interest / rewards from Coinbase Earn** — income at receipt.

Step 3: Import into CryptoLens

Drag the CSV into cryptolens.uk/import. The Coinbase format is auto-detected; we apply HMRC Section 104 pooling, same-day matching, and the 30-day bed-and-breakfast rule automatically. Staking rewards route into the income column separately so you can report them on SA100 rather than SA108.

Step 4: Read the tax summary

Open the /tax page after your import. The dashboard shows:

- **Net gain** (gross gains minus allowable losses) - **Annual Exempt Amount applied** — £3,000 for 2026/27 - **Taxable gain** — what actually flows into your SA108 - **Estimated tax** at basic (18%) and higher (24%) rate

Pick your tax band (basic if your total income is under £50,270; higher above) — that's your CGT bill on crypto.

Staking / income totals are shown separately for your SA100 box.

Step 5: File

For 2026/27, the online Self Assessment deadline is 31 January 2028. Fill in the SA108 with the totals from CryptoLens (number of disposals, total proceeds, total costs, total gains, total losses, AEA used). Attach the CSV/PDF summary as supporting evidence — HMRC doesn't require you to send it with the return, but you must keep it for at least six years.

If you've never filed Self Assessment before, register with HMRC by 5 October 2027. It takes about ten minutes and unlocks the online portal.

Common gotchas even Coinbase-only users hit

- **You forgot the auto-conversions.** Coinbase sometimes auto-converts small balances into a wrapper before selling. These count as disposals. CryptoLens picks them up because the CSV shows them; just don't hand-edit the file to remove "small" rows. - **You have Coinbase Wallet transactions too.** Coinbase (the exchange) and Coinbase Wallet (the self-custody browser wallet) are separate. If you moved crypto to Coinbase Wallet and then swapped there via Uniswap, those swaps are additional disposals not on your Coinbase CSV. Scan your Coinbase Wallet address separately. - **You received a nudge letter.** If HMRC has sent you a crypto nudge letter, they already have CARF data on your Coinbase activity. Do not ignore it — see our <a href="/blog/hmrc-crypto-nudge-letter">nudge-letter guide</a>.

The whole thing takes about 20 minutes

For a Coinbase-only user with a normal-shaped holding, from CSV export to filed SA108 figures is genuinely a 20-minute exercise using CryptoLens. Pro is £4.99/month with a 30-day money-back guarantee. If your tax situation is more complex (multi-chain, DeFi, NFTs, self-custody, prior-year losses to bring forward), it takes longer — but the arithmetic is still done for you.