A married couple have requested a reallocation of their joint income components for 2019. The tax inspector issues a supplementary tax assessment to the husband and grants a tax refund to the wife. In the supplementary tax assessment, the tax inspector charges €3,681 in tax interest, which is more than the couple originally owed together. The husband objects. He does not consider it fair that the tax inspector charges more tax interest in the event of a reallocation.
Initially, too little interest was charged
He points out that the total tax interest on the original assessment notices amounted to just €2,675. As a result of the reassessment, his tax interest has therefore risen sharply. However, the tax inspector acknowledges that he had made a mistake in the original assessments. He had calculated the interest over too short a period. In fact, the total tax interest should have been €6,889. The man has therefore actually benefited from the mistake.
Invocation of the ECHR and proportionality
The man argues that the rate of tax interest is contrary to higher-ranking legislation. He invokes, amongst other things, the European Convention on Human Rights and the principle of proportionality. The court refers to a judgment of the Supreme Court dated 16 January 2026. In that judgment, the Supreme Court did indeed rule that the tax interest rate for corporation tax is too high, but that this does not apply to income tax. The interest rate is not disproportionate. After all, the incentive to file tax returns accurately and on time is a legitimate aim.
Amendment by request, not by objection
In the alternative, the man invokes the prohibition on reformatio in peius. The tax interest must not, as a result of the objection, exceed the amount set out in the original assessments. The court does not agree with this argument. The tax interest was, in fact, adjusted as a result of the request for a different allocation, not as a result of the objection. The fact that the tax inspector had charged too little interest in the original assessments does not alter this. The court declares the appeal unfounded.