CEX vs DeFi Crypto Tax UK: Key HMRC Differences
HMRC pools tokens across exchanges and DeFi, but the tax records look very different. Learn the key UK crypto tax differences and risks.
Most UK crypto investors use both centralised exchanges and DeFi. You buy ETH on Coinbase, bridge it to Arbitrum, swap it on Uniswap, stake it on Lido, and eventually sell some back to GBP on Kraken. That is a completely normal workflow, and it creates a tax calculation problem that no single platform can solve on its own.
UK matching combines relevant history across your platforms. Same-day and following-30-day acquisitions are matched before the Section 104 pool. But the type of activity (exchange trade, swap, LP removal, staking reward) determines whether the event is capital gains, income, or non-taxable. The rules are the same; the complexity is not.
This guide compares how exchange trades and DeFi activity are taxed, explains why separate platform calculations can omit relevant history, and shows what a correct combined calculation looks like.
The tax basics: same rules, different complexity
UK crypto tax follows two tracks: Capital Gains Tax (CGT) on disposals, and Income Tax on rewards and earnings. Both apply regardless of whether the activity happened on an exchange or on-chain.
| Activity | Centralised exchange | DeFi | Tax treatment |
|---|---|---|---|
| Buy crypto with GBP | Buy order | On-ramp (rare) | Acquisition (no tax) |
| Sell crypto to GBP | Sell order | Off-ramp (rare) | CGT at 18% / 24% |
| Token-to-token swap | Convert | Uniswap, Curve, 1inch | CGT (disposal of outgoing token) |
| Staking rewards | Coinbase Earn, Kraken staking | Lido rebases, CRV gauge | Review receipt facts and apply the appropriate income treatment |
| LP position add | N/A | Uniswap, Balancer, Curve | Can create disposals where beneficial ownership transfers |
| LP position remove | N/A | Uniswap, Balancer, Curve | Review the position, rights surrendered and assets received |
| Bridge transfer | N/A | Hop, Arbitrum, Optimism | Check that beneficial ownership and the underlying asset are retained |
| Deposit / withdrawal | Send / Receive | Aave supply, WETH wrap | Depends on beneficial ownership and the rights involved |
A protocol label alone does not establish a non-taxable transfer. HMRC's beneficial-ownership guidance requires the arrangement's terms to be examined. See the Aave lending guide and wrapping guide for the distinctions that need review.
Exchange activity is straightforward: buy, sell, convert, earn. DeFi introduces LP positions, protocol-specific staking, bridging, wrapping, and interactions that require protocol-aware classification. The underlying tax rules are identical; the difficulty is in correctly identifying what happened.
Exchange trades: straightforward but not automatic
Exchange trades map cleanly to HMRC tax events. A buy is an acquisition. A sell is a disposal. A convert is both. Staking rewards are income. Deposits and withdrawals between your own wallets are non-taxable transfers.
The catch is that your exchange's tax report uses the wrong cost basis method. Coinbase uses FIFO, Binance offers multiple methods (none of which are Section 104), and Kraken shows raw trade data without any gain calculation at all. The same shortfall applies to Crypto.com's app and card exports.
FIFO is not Section 104
If an exchange report uses FIFO (first in, first out), its gains need to be reconciled to UK matching: same-day acquisitions, then acquisitions in the following 30 days, then Section 104 pooling. Check the method and complete account-wide history before relying on a report for your Self Assessment.
DeFi: where classification needs more context
DeFi transactions are harder to classify because the raw on-chain data does not tell you the intent. A Uniswap V3 LP position involves multiple token transfers, NFT mints, and internal calls. Review the ownership and rights transferred on entry or withdrawal and the nature of any return. A transaction label alone does not settle its treatment.
| DeFi interaction | Evidence and treatment to review | Mistake to avoid |
|---|---|---|
| Uniswap LP add | Can create disposals where beneficial ownership transfers | Recording the new position without examining the deposited assets |
| Bridge (Arbitrum, Optimism) | Check retained beneficial ownership and underlying asset | Treating a bridge label alone as proof of basis carry |
| WETH wrap/unwrap | Check a direct wrap preserves ownership and economic rights | Confusing a direct wrap with a swap routed through WETH |
| Aave deposit | Examine contract terms and beneficial ownership | Assuming every deposit is taxable or non-taxable |
| Staking rewards (Lido, CRV) | Review the receipt and nature of the return | Ignoring receipt evidence or the applicable income rules |
| LP fee collection | Determine whether the return is income or capital | Assuming every payment called an LP fee is income |
Misclassification can change gains and later pool costs. Where the evidence supports an own-asset transfer, recording a disposal can introduce an unsupported gain. Where ownership or rights changed, carrying basis without review can miss a disposal. For more on bridge classification, see is bridging crypto taxable in the UK.
The S104 pool doesn't know where you bought
This is the core reason you cannot use separate tools for exchange and DeFi activity. The Section 104 pool for ETH includes every ETH acquisition you have ever made, regardless of source:
Combined S104 pool example
1. Buy 1 ETH on Coinbase at £1,800 → pool: 1 ETH, cost £1,800
2. Swap 2,000 USDC → 1 ETH on Uniswap (ETH at £2,000) → pool: 2 ETH, cost £3,800
3. Receive 0.1 ETH staking on Lido (ETH at £2,200) → pool: 2.1 ETH, cost £4,020
Average cost per ETH: £4,020 ÷ 2.1 = £1,914.29
Sell 1 ETH on Kraken for £2,500. Gain = £2,500 − £1,914.29 = £585.71
Coinbase only: gain = £2,500 − £1,800 = £700 (wrong)
The £114 difference here is from just three transactions. A user with hundreds of DeFi interactions feeding the same S104 pool will see much larger errors in any single-platform report.
CARF reporting and your exchange records
Under the Crypto-Asset Reporting Framework (CARF), in-scope UK reporting cryptoasset service providers began collecting reportable data on 1 January 2026. Their first reports cover the 2026 calendar year and are due to HMRC between 1 January and 31 May 2027. The provider definition and reporting-jurisdiction rules determine who reports; an exchange name or FCA registration alone does not establish it.
Provider reports contain prescribed identity and annual transaction information. Your tax calculation may need earlier purchases and activity from other platforms that one provider cannot see. Reconcile those records before drawing conclusions from a difference; a difference alone does not establish an error or guarantee an HMRC enquiry.
The CARF + DeFi gap
A business with control or sufficient influence over a DeFi service may also fall within CARF. Purely unmediated smart-contract activity may have no reporting provider, but that does not settle the user's tax obligations. HMRC explains the scope in its trading-platform guidance. The CARF 2027 readiness page walks through the reconciliation step by step.
Income tax: staking, rewards, and yield
Determine the nature of the return before applying income or capital treatment. HMRC's DeFi return guidance says this depends on how the arrangement is structured. A reward or LP fee label alone does not establish the result.
Exchange income is explicit: Coinbase labels it "Coinbase Earn" or "Staking Income". DeFi income is harder. Lido stETH rebases happen at the protocol level without generating a transaction in your history. CRV gauge rewards require decoding the Minter contract logs. LP fee collection on Uniswap V3 is embedded within position management calls.
All income events, exchange and DeFi alike, enter the Section 104 pool as acquisitions at FMV. This increases your cost basis, which reduces future capital gains. For a full breakdown, see DeFi income vs capital gains.
Gas fees: the DeFi-only allowable cost
When you trade on an exchange, the spread and trading fees are baked into the execution price. These are not separately deductible for CGT purposes.
DeFi transactions are different. You pay gas fees in ETH (or the network's native token) for every on-chain interaction. HMRC treats gas fees as an allowable cost, which means they directly reduce your taxable gain on each disposal.
For active DeFi users, cumulative gas fees over a tax year can be significant: hundreds or even thousands of pounds. Failing to include them as allowable costs means overpaying CGT. This is an advantage DeFi users have that exchange-only users do not.
Why you need one tool for both
The fundamental constraint is that HMRC matching rules operate across all platforms. The same-day and B&B rules match disposals against acquisitions regardless of where they happened. Sell ETH on Coinbase and buy ETH on Uniswap on the same day? Same-day rule applies. Sell on Kraken and swap USDC→ETH on Curve within 30 days? B&B rule applies.
No tool that only sees one side can detect cross-platform matching. And since the Section 104 pool is per-asset (not per-platform), every acquisition and disposal must be in the same calculation for the average cost to be correct. A UK crypto tax calculator that ingests both exchange CSVs and on-chain wallet history is the only way to get this right without rebuilding the pool by hand.
How ChainTax reconciles exchange + DeFi
ChainTax is built for users who trade across both exchanges and DeFi. The workflow:
- Import exchange CSVs. Upload from Coinbase, Binance, or Kraken. The format is auto-detected and every transaction is classified for HMRC.
- Connect DeFi wallets. Add your wallet addresses across Ethereum, Arbitrum, Optimism, Base, and Polygon. 34 protocol-specific classifiers handle the on-chain activity.
- Unified calculation. All sources feed the same Section 104 pools. Same-day and B&B matching operates across exchange and DeFi transactions. Gas fees are included as allowable costs.
- UK tax output for review. Calculated SA108 box values come from the combined data. Every calculated disposal shows the matching rule used, the S104 pool state, and the gain working.
You can try the classification engine for free using the transaction explainer. Paste any transaction hash to see how it is classified.
Choosing a tool to handle both sides? See how ChainTax stacks up against the other UK crypto tax tools.
Get your complete crypto tax picture
Import your exchange trades and connect your DeFi wallets. ChainTax reconciles supported activity into one UK calculation with Section 104 pools, cross-platform matching, visible evidence checks, and SA108-oriented totals. Free for up to 200 transactions.
Common questions
Why can't I use separate tools for exchange and DeFi tax?
Combine the acquisition and disposal history for the same asset across your wallets and exchanges. Separate platform calculations can omit relevant history and produce an unsupported cost basis. Apply same-day and following-30-day matching before the Section 104 pool.
Does HMRC tax centralised exchange and DeFi crypto differently?
UK tax depends on what the transaction does, not whether it happens on an exchange or through DeFi. Sales and token swaps can create disposals. Lending, liquidity positions and returns need their rights, beneficial ownership and economic facts examined.
How does Section 104 pooling work across exchanges and DeFi?
Section 104 maintains a single weighted-average cost pool per token across all platforms. If you buy 1 ETH at £1,000 on Coinbase and 1 ETH at £2,000 via Uniswap, your pool cost is £1,500 per ETH. Same-day and 30-day bed & breakfast rules are applied first, then the pool handles remaining disposals.
What is CARF and does it cover DeFi?
CARF applies to businesses that meet the reporting cryptoasset service provider definition. A business with control or sufficient influence over a DeFi service may be in scope; the DeFi label alone does not decide it. In-scope providers began collecting reportable data in 2026 and first report 2026 data to HMRC by 31 May 2027.
Do I need to report DeFi activity if I only used exchanges before?
Review the DeFi activity together with your exchange history. Whether a transaction creates a disposal or income depends on its facts, and whether you must report it depends on the applicable tax-year reporting rules and your circumstances. A bridge, staking action or reward claim alone does not answer every part of that question.
This article is for informational purposes only and does not constitute tax, legal, or financial advice. Tax rules can change, and individual circumstances vary. Always consult a qualified tax adviser before filing your Self Assessment return. HMRC guidance referenced: CRYPTO22000 (capital gains on disposals), CRYPTO61000 (DeFi income), CRYPTO10100 (definition of cryptoassets), s104 TCGA 1992, s106A TCGA 1992 (B&B rule). CGT rates and annual exempt amounts from GOV.UK (2024/25, 2025/26 and 2026/27 tax years).
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