The line for crypto
In the 2025 return and later, go to the part on bank accounts and other assets (bankrekeningen en andere bezittingen), tick Cryptobezittingen and enter the amount. For 2024 and earlier, crypto went under Overige bezittingen, as Andere bezittingen.
The value to enter
The value at 0:00 on 1 January, according to the price on the exchange platform you used.
If you choose the actual return
Then the return also asks for the value on 31 December and the total value of your purchases and sales during the year.
Keep proof
Keep exchange statements and a record of balances and prices around 1 January, also for coins in your own wallets. With Pro, the fill-in help shows each figure next to its line in the return.