Cryptocurrency taxation : how to declare your gains without making mistakes with the tax authorities

📊 In short — Since 2019, gains made on cryptocurrencies in France are subject to taxation. Whether it's selling Bitcoin for euros or using your digital assets for purchases, every operation must be declared via forms 2086 and 2042-C. The tax rate is 30% (flat tax), unless you opt for the progressive tax scale. Errors or omissions expose you to fines of up to 1 500€ per undeclared account, not to mention surcharges of 10 to 80% on the tax due. To avoid mistakes, it's better to understand the rules before declaring, or to be assisted by a specialized tool.

🎯 Key points to remember

🔹 Only disposals of cryptocurrencies against fiat currency (euros, dollars) are taxable — not exchanges between cryptos

🔹 The 305€ allowance threshold applies: below it you are not taxed, but declaration is still mandatory

🔹 Forms 2086 and 2042-C must be completed on impots.gouv.fr during your annual declaration

🔹 The default rate is 30% (17.2% social contributions + 12.8% income tax)

🔹 You can opt for the progressive tax scale, which can be more advantageous depending on your situation

🔹 Crypto accounts held abroad must be declared via form 3916-bis, under penalty of a fine

🔹 Staking and mining fall under a different regime (BNC) and are not declared via form 2086

🏛️ Understanding the tax framework for cryptocurrencies in France

Since January 2019, France taxes gains made on cryptocurrencies. But beware: simple holding is never taxable. Only disposal operations — selling your bitcoins for euros, buying a good with Ethereum — trigger a tax obligation. This is a fundamental distinction that many investors forget.

This distinction is based on a simple logic: as long as your digital assets remain in your wallet, they are unrealized values. The moment you convert them into legal tender or use them for a concrete transaction, you crystallize a gain or a loss. It is this precise moment that the tax authorities intend to capture.

The French system relies on the form 2086, which details each disposal operation, and on the supplementary declaration 2042-C, which synthesizes the final result. Understanding this mechanism avoids the most costly mistakes.

The single flat-rate levy (PFU): how the 30% flat tax works

By default, your cryptocurrency gains are subject to the single flat-rate levy (PFU) of 30%. This single rate aggregates two levies: 17.2% for social contributions and 12.8% for income tax. It applies automatically, regardless of your marginal tax bracket.

This system has one advantage: it is predictable and simple. If you realize a €10,000 capital gain, you know the tax will be exactly €3,000, no matter your overall income. This is particularly interesting for high earners, for whom the progressive scale could have exceeded 50%.

But there is an alternative. Since 2023, you can opt for taxation under the progressive scale, more advantageous if your income is moderate. This option must be decided at the time of filing and applies to all your investment income for the year.

Capital losses: how to deduct them from your capital gains

If you made losses on certain operations, they are not lost for tax purposes. Capital losses are fully deductible from the capital gains of the same fiscal year to determine your net taxable base. A concrete example: you gain €15,000 on a Bitcoin sale but lose €5,000 on an Ethereum disposal. Your taxable base becomes €10,000.

This pairing is automatic: the tax authority does not ask you to choose which losses to offset. You simply need to declare all your operations, and the administration calculates the net balance. This is one reason why meticulous tracking of every transaction is crucial.

📋 The forms to complete: detailed how-to

Declaring cryptocurrency gains relies on two main forms. Many get lost in administrative mazes for lack of understanding how to activate and complete them. Here is the path to follow, step by step.

Activate forms 2086 and 2042-C on impots.gouv.fr

The first surprise for many: crypto forms do not appear by default on impots.gouv.fr. You must activate them manually. Without this action, you will get the impression that the site offers no space to declare your cryptocurrencies, which may prompt you to neglect this obligation. A costly mistake.

During the online declaration, go to step 3 “Revenues”. Click on “Supplementary declarations” at the top of the page and check box no. 2086 (capital gains/losses on digital assets). If you hold crypto accounts abroad, also check no. 3916-bis. Validate these choices, and the system readjusts automatically. The forms then appear in the left menu.

This mechanism may seem tedious, but it reflects an administrative choice: to clarify the tax status according to each profile. Not activating these annexes is equivalent to implicitly declaring that you have no cryptocurrency transactions.

Filling in form 2086: detail each disposal

Form 2086 is the technical document that summarizes your disposal operations. For each cryptocurrency sale, you must provide three key elements: the net disposal price, the total value of your portfolio at the date of that sale, and the capital gain or loss calculated according to the method of the weighted average price (PMP).

The latter point is tricky. The weighted average price requires reconstructing the market value of all your digital assets at the exact time of each disposal, even if you hold Bitcoin on three different platforms. With a few transactions per year, it's manageable. With fifty, a hundred or more, it becomes an administrative nightmare — hence the importance of using a tool.

An example simplifies the process. Suppose you buy 1 Bitcoin at €30,000 and 10 Ethereum at €1,000 each (portfolio = €40,000). Six months later, Bitcoin has doubled and you sell 0.5 for €30,000. The form requires you to declare this disposal, the sale price (€30,000), the value of your portfolio at that date (say €70,000 if prices rose), and the capital gain (which will not be the €15,000 gross gain, but recalculated according to the PMP).

Report the result on form 2042-C

Once form 2086 is completed and validated, the overall result is automatically synthesized. This amount must be reported on the supplementary declaration 2042-C, which determines the final tax regime. Two boxes interest you: box 3AN for net capital gains (subject by default to the PFU) and box 2OP if you opt for the progressive scale.

Before validating your declaration, take a moment to compare the two regimes. If your annual income is high (above €160,000), the marginal income tax already exceeds 45%, which makes the 30% PFU very attractive. If you're early in your career or on sabbatical leave, the progressive scale can save you several thousand euros.

⚙️ Special operations: staking, mining and internal exchanges

The basic regime does not cover all situations. Some crypto activities follow radically different rules that it is imperative to distinguish.

Staking and mining: a distinct regime (BNC)

If you receive staking or mining rewards in 2025, this is not declared on form 2086 — it is taxable income upon receipt. These revenues fall under non-commercial profits (BNC) and must be declared via the 2042-C Pro, boxes 5KU (micro-BNC) or 5JG (standard regime).

The distinction depends on the nature of the operation. Staking consists of locking your assets to validate transactions and receive rewards — it is a lucrative activity. Mining is providing computing power for the same purpose. In both cases, you generate active income, not passive capital gains.

Practically, if you receive 0.5 Ethereum per month as a staking reward, each receipt is taxable at its market value that day. If you receive the Ethereum in a month when it is worth €2,000, you must declare €1,000 of income, even if the price later drops to €1,500. This is what English speakers call “unrealized loss”.

Exchanges between cryptocurrencies: why they are not taxable (for now)

Do you exchange Bitcoin for Ethereum or stablecoins? No tax for now. As long as you stay within the digital asset ecosystem without touching legal tender, no capital gain is crystallized under French tax rules. This rule is very advantageous for traders who wish to reallocate their portfolio.

It is based on a logic: without conversion to fiat (euros, dollars), there is no realized income under French law. However, this interpretation could evolve. The tax administration is closely monitoring these chains of transactions and could, tomorrow, tax certain exchanges as taxable operations. Following the crypto tax news helps you stay informed of changes.

📊 Practical cases: three calculation examples

Theory sheds little light without concrete examples. Here are three everyday scenarios to illustrate how the tax really works.

Case 1: a simple capital gain on a single operation

Léa buys €5,000 of Bitcoin and sells it six months later for €8,000. Gross capital gain: €3,000. Flat tax: €3,000 × 30% = €900 tax. Net gain: €2,100. This is the simplest scenario, where no complication arises.

Case 2: capital gain and loss on two different assets

Marc makes two disposals during the year. First, he sells €4,000 of Bitcoin for €7,000 (capital gain of €3,000). Then he disposes of €6,000 of Ethereum for €5,000 (capital loss of €1,000). Net taxable base: €3,000 − €1,000 = €2,000. Tax: €2,000 × 30% = €600. The two operations fully offset each other.

Case 3: calculation with the complex weighted average price (PMP)

Sophie owns a diversified portfolio. She buys 1 Bitcoin at €30,000 and 20 Ethereum at €1,000 each (portfolio = €50,000). Six months later, Bitcoin is worth €50,000 and Ethereum €2,000 (portfolio = €50,000 + €40,000 = €90,000). She sells 0.5 Bitcoin for €25,000. The capital gain is not simply (25,000€ − 15,000€) = €10,000. According to the PMP, it must be calculated as: capital gain = 25,000€ − [(30,000€ × 25,000€) / 90,000€] = 25,000€ − 8,333€ = €16,667 of real capital gain. Tax: €16,667 × 30% ≈ €5,000.

This example shows why the PMP is delicate to handle. It considers the ratio between the capital invested and the current total value, which can be surprising at first but reflects an asset allocation logic.

🚨 Pitfalls to avoid and penalties in case of error

The tax administration is strengthening its controls. With automatic exchange of information between platforms (via MiCA and other directives), the administration now knows a lot about your operations. Errors no longer go unnoticed.

Fines for undeclared accounts

If you own an account on Binance, Kraken or Coinbase (foreign sites) and forget to declare it via form 3916-bis, the sanctions are severe: €750 fine per account, raised to €1,500 if the account value exceeds certain thresholds. The total ceiling is €10,000 per year, but it is already painful.

For French residents, this declaration is mandatory, without exception. The only platforms exempt are those based in France (rare in the crypto ecosystem).

Surcharges on underpaid tax

Beyond fixed fines, the administration can apply a 10% surcharge on the tax due if it detects an under-reporting. If you had not declared a €20,000 capital gain, that means €6,000 of unpaid tax. The surcharge would be €600. But if the fraud is intentional, this surcharge can rise to 40% or even 80%.

Late payment interest

Each quarter of unpaid tax automatically generates late payment interest, generally calculated at a legal rate revised periodically. It is an invisible cost that accumulates quickly.

Voluntary regularization: your best ally in case of omission

If you discover an omission after you have already filed, voluntary regularization is always preferable to waiting. The French administration rewards initiative: it generally removes surcharges and only collects the tax due, plus late interest at the minimal rate. This is an implicit agreement that works in 95% of cases.

💼 Declaring crypto accounts abroad: form 3916-bis

This aspect is often overlooked, wrongly. If you hold a wallet on a foreign platform, its declaration follows distinct rules.

Who must fill in the 3916-bis?

All French (and Monegasque) residents holding a cryptocurrency account with a provider located outside France. Whether it is active or closed, it does not matter: the form must be completed in the year of closure as well. Each account requires a separate form.

Where to fill in form 3916-bis?

During your online declaration on impots.gouv.fr, go to step 3 “Revenues”, click on “Supplementary declarations” and check box no. 3916-bis. The document then appears on the left and guides you to provide the platform's identity, its full contact details, and the annual movements (deposits, withdrawals).

The main platforms are already listed in a pre-filled list: Binance (Malta), Kraken (London), Coinbase (Dublin), eToro (Cyprus), Crypto.com (Malta). If your platform is not listed, you must search for it manually.

What are the penalties if I forget?

As mentioned, the fine is at least €750 per account, doubled beyond €50,000. If the provider's country has not concluded a convention with France against tax fraud, the fine is raised to €10,000 straight away. Most countries are covered by these conventions, but it is prudent to check for your specific platform.

🛡️ Strategies to legally optimize your taxation

Tax optimization is not fraud if it complies with the law. Here are some approaches to explore.

Opt for the progressive scale rather than the flat tax

If your total income is moderate, taxation under the progressive scale can be very advantageous. For incomes up to €11,000 annually (first bracket), the marginal tax rate is 0%. For those up to €43,000, it reaches 11%. Compare this scale to the 30% flat tax and you understand the issue.

Warning: this option must be explicitly indicated during the declaration (box 2OP on form 2042-C) and applies to all your investment income for the year. A tax simulator helps you calculate the gain or loss before deciding.

Use losses to offset gains

If you have made losing trades, they will automatically be offset against gains. But nothing forces you to deliberately realize losses. However, if you plan to sell an asset at a loss for other reasons, take the opportunity to clean up your taxable base for the year. It's an opportunity, not an obligation.

Staking hostage: exploit the timing of income

If you receive staking rewards regularly, you can consider letting them accumulate until certain thresholds — a year in which you have little other income, for example. Staking BNC income is added to employment income and follows the progressive scale. If one year you have no salary, taxing €50,000 of staking under the progressive scale instead of the 30% flat tax can represent significant savings.

Check whether your capital losses are carry-forwardable

In France, cryptocurrency capital losses generally cannot be carried forward to the next year (unlike stock market losses). This point is crucial: if you make a large loss in 2025 and a large gain in 2026, you cannot offset them. Plan your disposals accordingly if you anticipate a major transaction.

📱 Tools to simplify your life

With a large number of transactions, filling in forms manually quickly becomes impossible. Solutions exist to automate and secure this process.

Specialized platforms sync your crypto accounts via API or CSV and automatically generate the amounts to declare. They calculate the tax according to the PMP, create auditable reports, and spare you manual errors. Once the report is generated, you just copy the figures onto impots.gouv.fr — which takes a few minutes instead of several hours.

For occasional declarants (a few transactions per year), an Excel spreadsheet is enough. For active traders or passive holders who have accumulated operations over several years, investing €100 to €300 in an automated tool will quickly pay off in time saved and errors avoided.

The crypto tax news in France changes regularly. Subscribing to a specialized newsletter or regularly consulting the official tax authority's resources keeps you informed of developments.

🔍 Frequently asked questions that remain

Do I have to declare if I'm in a net loss?

Yes. Even if your annual balance is negative, capital losses must be declared via form 2086. You will not pay tax, of course, but the administration keeps a record. This can prove useful later to justify operations in case of audit.

What if I slightly exceed the €305 threshold?

The €305 threshold applies only to taxation. If your net capital gain is €400, you are taxed on (400€ − 305€) = €95, i.e. 95€ × 30% ≈ €28.50 of tax. You are liable, but the amount remains limited.

Airdrops and free tokens: are they taxable?

Yes, at the time of receipt. An airdrop is a form of income: if you receive 100 tokens worth €10 each, you declare €1,000 of taxable income that day. If those tokens later fall to €2, it's too late — taxation is based on the value at receipt, not on the value at later sale. This point frustrates many holders.

Can I pay my taxes in cryptocurrency?

No, not in France. The French state requires payment in euros or by bank debit. Only very few countries (El Salvador since 2021, certain Swiss municipalities via Plan ₿) currently accept cryptocurrencies for tax payment.

📌 Summary of key steps to not forget

Before each tax season, remember this checklist:

✅ Gather the complete history of all your 2025 transactions (disposals, purchases, exchanges)

✅ Calculate your net capital gain/loss according to the PMP

✅ Check the €305 allowance threshold

✅ Activate forms 2086 and 2042-C on impots.gouv.fr

✅ Declare all foreign crypto accounts via 3916-bis

✅ Compare PFU (30%) and the progressive scale for your situation

✅ Complete the forms and validate your declaration before your department's deadline

✅ Keep all supporting documents for 6 years (transaction statements, PMP reports, etc.)

The crypto taxation in detail requires rigor, but it is not insurmountable. The essential thing is to take the time to understand the rules and to equip yourself if the volume of transactions justifies it. Tax peace of mind starts with organization.