Box 3 is the third box in the Dutch personal income tax system. It taxes notional returns on net worth held in savings, shares, second homes, receivables, and similar assets, minus debts, above the annual tax-free allowance (heffingvrij vermogen).
The Hoge Raad ruled in December 2021 that the pre-2017 flat notional-return system breached the European Convention on Human Rights for many taxpayers. Successive judgments through 2024 confirmed that the bridging legislation (Wet rechtsherstel box 3) and the subsequent Wet overbruggingswet box 3 still conflict with the Convention where the actual return is lower than the notional return. The legislature plans to replace the regime with a tax on actual returns, currently targeted for 2027 or 2028.
For 2026 the transitional regime continues, with taxpayers able to request the actual-return route where it produces a lower base. Affected filers should track their asset categories and supporting evidence carefully.