Calculating your crypto capital gain, with a worked example

Updated on 25 October 2026

In France, the capital gain on a sale of crypto is calculated neither token by token nor "first in, first out" (FIFO). It is calculated on the whole portfolio, on each taxable disposal, with the formula of form 2086 (article 150 VH bis of the CGI, the French tax code). Here is the method, then a complete example over two sales.

The formula

Plus-value = Prix de cession − (Prix total d'acquisition × Prix de cession ÷ Valeur globale du portefeuille)

• Sale price : what you receive in euros (or the value of the goods paid for in crypto), less the selling fees.
• Overall portfolio value : the value of all your crypto just before the sale, across all exchanges, wallets and protocols, DeFi positions included (tokens lent, staked, in a liquidity pool).
• Total acquisition cost : everything you have paid in euros to buy crypto, less the share already "used up" by previous sales.

Swaps between crypto assets (BTC for ETH, ETH for USDC…) are not taxable disposals: they change neither the total acquisition cost nor the calculation.

Example: two sales in the year

You have bought €10,000 worth of crypto since 2022. You have swapped between crypto assets and put part of it into DeFi: no tax at this stage.

First sale, in March 2026

The total acquisition cost remaining for later sales is 10,000 − 2,000 = €8,000.

Purchase, then second sale, in October 2026

Meanwhile, you buy back €1,000 of crypto: the total acquisition cost becomes 8,000 + 1,000 = €9,000.

Net capital gain for the year: 3,000 + 4,200 = €7,200, reported in box 3AN. At the 31.4% flat tax (PFU) applicable to disposals made in 2026, the tax comes to about €2,261.

What most often skews the calculation

• Leaving DeFi out of the overall value : an overall value that is too low inflates the allocated share and lowers the declared capital gain, which a tax audit can correct.
• Calculating with FIFO or token by token, as in other countries.
• Not deducting the share already used up of the acquisition cost after a first sale.
• Counting swaps between crypto assets as sales.
• Forgetting selling fees, which reduce the sale price.

€305 threshold and capital losses

If the total of your sale prices for the year does not exceed €305, no capital gain is taxable. A net capital loss can only be offset against crypto capital gains of the same year : it cannot be carried forward.

The hardest part: the overall value at each date

The formula is simple; what takes time is finding the value of the whole portfolio on the exact date of each sale, DeFi positions included. Bilan DeFi reconstructs it from the blockchain and your exchanges connected read-only, then prepares the lines of form 2086.

See also: crypto taxation in France, declaring your crypto (form 2086), DeFi taxation.

Frequently asked questions

How is the capital gain on crypto calculated in France?

Gain = sale price − (total acquisition cost × sale price ÷ overall portfolio value). The calculation covers the whole portfolio, on each sale for euros, not token by token.

Is FIFO accepted for crypto in France?

No. The French method is the weighted average price of the whole portfolio, set by article 150 VH bis of the CGI and used in form 2086.

Are transaction fees deductible?

Disposal fees reduce the sale price. Purchase fees are part of the acquisition cost.

Should DeFi positions be counted in the portfolio value?

Yes. The overall portfolio value includes all your crypto, including assets lent, staked or deposited in a liquidity pool.

General information, not tax advice. The rules change with every finance act and depend on your situation. For a complex case (regular activity, large amounts, a tax audit), have it checked by a chartered accountant or a tax lawyer.