Collect the complete transaction history
Export trades, deposits, withdrawals, fees and rewards from every exchange and wallet used. Preserve transaction identifiers, dates, asset quantities and available fiat values. Download records before closing an account or losing access to an old platform.
Reconcile opening holdings plus receipts less disposals and transfers to closing holdings. A bank-only review misses swaps and payments made entirely on-chain. Wallet addresses help match activity, but a public address alone does not prove who owned the assets at each time.
Classify before calculating
Identify sales, exchanges, gifts and payments as categories covered by the disposal definition. Match transfers between wallets owned by the same person so they are not mistakenly recorded as both a sale and a new purchase merely because they appear as withdrawal and deposit.
Separate mining-acquired assets, staking or other rewards, employment payments and unusual arrangements for analysis. The special rate is not a blanket rule for everything described as “crypto income.” Keep acquisition costs, fees and valuation evidence with the transaction record.
Track same-year gains and losses
For a simplified example, assume €12,000 of qualifying disposal gains and €4,000 of qualifying disposal losses in the same year. Net qualifying gain is €8,000; at 8%, tax is €640. This assumes the amounts and classification have already been established correctly.
If qualifying losses exceed gains, the excess cannot be carried to later years under section 20E or surrendered through group relief. Do not merge that balance with ordinary business losses. Keep annual totals separate even when the same wallet is used continuously.
Create a reviewable evidence pack
Keep raw exports unchanged and record corrections in a separate working file. Explain missing prices, duplicate transactions and unsupported cost amounts. Reconcile the final calculation to holdings and cash movements, with unresolved items clearly identified.
For foreign taxes, use the double-tax checklist. The ordinary loss guide explains why business-loss treatment should not be assumed for the special crypto regime.