Tax Interest (Belastingrente)
Tax interest (belastingrente) is interest charged by the Tax Authority on tax that you paid late or underpaid. The interest starts accruing from July 1 of the year following the tax year. For example, if you file for 2025 and your final assessment isn't issued until October 2026, you pay tax interest from July 1, 2026. The tax interest rate is significantly higher than savings rates: in 2025 it is 7.5% for income tax. You can avoid tax interest by filing before May 1, so the Tax Authority can issue your assessment before July 1. Another option is to request a sufficiently high provisional assessment.
Example
You don't file your 2025 return until September 2026. Your final assessment of €3,000 is issued in December 2026. You pay tax interest of 7.5% on €3,000 from July 1 to December 31 = half a year = €112.50 extra.
Why does this matter?
Tax interest is an often forgotten expense. By filing on time (before May 1) or requesting a provisional assessment, you avoid unnecessary interest charges. The 7.5% interest rate is substantial – compare that to the interest on your savings account.
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