I Didn't Declare My Cryptocurrencies in Previous Years: What to Do Now

One of the most common cases in crypto tax advisory: the taxpayer who has been trading for years, didn’t know they had to declare, and now wants to regularize their situation before the tax authorities come knocking. Here’s the path to follow.

How Many Years Can the Tax Authorities Review?

The general statute of limitations for income tax is 4 years, counted from the end of the filing deadline for each tax year (usually June 30 of the following year).

In 2026, the tax authorities can review:

• Tax year 2025 (declaration due by June 2026) → not expired
• Tax year 2024 (declaration due by June 2025) → not expired
• Tax year 2023 (declaration due by June 2024) → not expired
• Tax year 2022 (declaration due by June 2023) → not expired
• Tax year 2021 (declaration due by June 2022) → expires in June 2026

The 2020 tax year would already be expired unless there has been any action by the tax authorities that interrupts the statute of limitations (e.g., a request for information, an audit, etc.).

Option 1: Voluntary Supplementary Declaration (Before a Request)

If the tax authorities have not yet contacted you, you can submit a supplementary declaration for each undeclared or incorrectly declared tax year.

Advantages of Voluntary Regularization:

• The penalty is significantly reduced (or eliminated if you regularize before any action by the tax authorities).
• If you file before a formal request: no penalty, only a surcharge for late filing.

Surcharges for Late Filing (Without Prior Request):

Without a prior request, there is no additional penalty. Only the surcharge and interest apply.

Option 2: If You’ve Already Received a Request

If the tax authorities have already notified you (e.g., a proposed parallel assessment, a request for information, or the start of a limited review), spontaneous regularization will no longer eliminate penalties. However:

• Cooperating and submitting documentation reduces penalties by 30%.
• You can argue mitigating factors (good faith, lack of intent to conceal).

How to Calculate What You Owe for Each Tax Year

For each undeclared year:

1. Obtain the complete transaction history for that tax year from each exchange.
2. Apply FIFO from the beginning of your activity (not just from that year).
3. Calculate the net gains and losses for the tax year.
4. Apply the tax rates in effect for that year (not the current rates).
5. Add the result to your savings tax base for that year.

Important: If you have losses in a later year and gains in an earlier year, you cannot retroactively offset them. Each tax year is calculated independently.

Income Tax Rates in Previous Years (Savings Tax Base)

What About Forms 172 and 173?

These informational forms have been mandatory since the 2023 tax year. If you didn’t file them:

• Penalty for late filing: from €200 to €20,000 depending on the volume of transactions.
• Voluntary regularization before a request can also be applied here.

Historical FIFO: The Biggest Technical Challenge

If you’ve been trading since 2017 or 2018 and have never declared, you’ll need to reconstruct your entire transaction history from the beginning to apply FIFO correctly. Purchases from 2017 determine the cost basis for sales in 2024.

Many exchanges don’t retain transaction histories for more than 5 years on their web platforms, but you can request them formally from the exchange (under GDPR access rights).

Conclusion: Act Before the Tax Authorities Do

The sooner you regularize, the lower the cost. The tax authorities are intensifying crypto data cross-checking and mass requests for information. Filing a spontaneous declaration without a request is significantly cheaper than waiting to be audited.

Updated: April 2026 | Tax Year: 2025