What is the taxable basis for savings & investments (grondslag sparen & beleggen)?
In the Netherlands, the wealth tax is levied on the income from your taxable basis for savings and investments (grondslag sparen en beleggen). Your taxable basis is the value at 00:00:00 on January 1st of your assets minus your debt and your tax-free capital of €50,000.
To see what contributes to your assets and what contributes to your debts you can go to the website of the Belastingdienst
Thomas has cash worth €40,000, a second home worth €80,000, crypto assets worth €5,000 and study debt of €10,000. Then Thomas's assets are (€40,000 +€80,000+€5,000) and his debts are worth (€10,000), he has a tax-free capital of €50,000. Thomas's taxable basis is then €125,000 - €10,000 - €50,000 = €65,000