Why it is on you
At a Belgian broker much is automatic: the stock-exchange tax is withheld, and soon the capital-gains tax too. For crypto that is not so. Crypto exchanges — Belgian ones included — do not withhold the capital-gains tax at source. It is your own responsibility to work out and declare the realised gain, just as an investor at Interactive Brokers or Trade Republic does for their shares.
That makes record-keeping more important than with a classic securities account. An exchange does not always give you a complete tax statement, and certainly not one aligned with the Belgian rules.
What you keep track of all year
To be able to determine your gain, you need a few data points per transaction:
| Data point | What it is for |
|---|---|
| Date of each buy, sell and swap | fixes the tax year and the order |
| Quantity and coin | the basis of the calculation |
| Price in euros at that moment | including for a coin-to-coin swap |
| Value on 31 December 2025 | the step-up reference for what you held before 2026 |
| Exchange fees | for documentation |
The tricky point is the swap from one coin to another. It counts, according to most sources, as a realisation, even without ever going into euros. For each swap you therefore need the euro equivalent at that moment. A portfolio in which you move often between coins thus generates far more taxable moments than there are euro sales.
The 31 December 2025 step-up
For crypto you bought before 2026, your taxable gain does not start from your purchase price but from the value on 31 December 2025. Only the gain built up after that date falls under the tax. If you cannot evidence that reference value, you risk the calculation falling back on your purchase price and the taxable gain coming out too high. So fix that valuation and keep it.
The full working of the step-up and of the exemption is in the article on crypto tax in 2026; the sum itself is made with the step-by-step guide to calculating crypto capital gains tax. The calculator reads your exchange's export for that — the per-exchange export guide says where to find it and what it contains.
What DAC8 changes
From 2026 the European DAC8 directive requires crypto platforms to pass data on their users to national tax authorities. For the Belgian tax authority that is an information flow that did not exist before. The practical lesson is simple: do not rely on invisibility, and make sure your own record matches what a platform can report.
Foreign accounts
Separately from the capital-gains tax, Belgium has a duty to declare foreign accounts. Whether, and in what form, that applies to a crypto platform depends on the nature of the platform and is not always clear. Check whether your exchange falls under it; the general mechanism is in the article on declaring a foreign account.
To be confirmed. The treatment of coin-to-coin swaps, staking, mining and airdrops, and the exact return boxes for crypto, are, at the time of writing, not confirmed in detail. Treat any figure that rests on them as uncertain.
Check your figures
Belfolio describes these steps for information. This is not tax advice. Check your situation with the FPS Finance or your accountant before you file.
Published 9 Aug 2026
Frequently asked questions
- Do I have to declare crypto if I sold nothing?
- As long as you realise no gain, there is no taxable moment under the capital-gains tax. Note: according to most sources a swap from one coin to another already counts as a realisation, even without passing through euros. A separate duty may exist for foreign accounts; check whether your platform falls under it.
- What if I use a foreign exchange?
- You remain taxable in Belgium on your worldwide gain. From 2026, foreign crypto platforms also share data with the Belgian tax authority under the DAC8 directive, so the assumption that a foreign exchange stays invisible is less and less true.