Dutch treasury faces hundreds of millions in extra costs over box 3 tax refund interest
The Dutch government may be liable for hundreds of millions of euros more than expected as a result of the Box 3 tax debacle, the Dutch tax authority (Belastingdienst) has confirmed. Taxpayers who overpaid capital gains tax under the former Box 3 system are not only entitled to refunds but may also be owed interest on those repayments, Het Financieele Dagblad (FD) reports.
The Ministry of Finance has not yet formally decided whether the interest—known as belastingrente in Dutch—will be paid. However, it said a decision is expected soon.
The Ministry appears to have been caught off guard by the additional cost, FD said. The possibility of interest payments was not addressed when the so-called "counter-evidence" procedure was created.
That procedure, which took effect on July 9, 2025, allows taxpayers to reclaim overpaid capital gains tax if they can prove that their actual income from savings and investments in a specific tax year was lower than the assumed return used by the tax authority to calculate their preliminary assessment. A special form, the "Opgaaf Werkelijk Rendement" (OWR), must be submitted to apply.
In a July 3, 2025 webinar for tax professionals, an expert from the tax authority stated that taxpayers whose only adjustment in their tax filing is a revised return on assets are entitled to receive interest. That statement signals that the government’s financial exposure may be far greater than previously estimated, Het FD argued. The Ministry of Finance has declined to give FD a comment until a formal decision is made.
The Box 3 wealth tax, which was based on assumed rather than actual returns on investments, was ruled unlawful by the Dutch Supreme Court in 2021. The refund mechanism introduced this month is part of the government's effort to repair the legal and financial consequences of the ruling.
