A mistake by the tax office means 155,500 people have paid a total of €30 million too much in interest on late payments.

The software glitch, which remained undiscovered from 2013 to 2021, was reported by freelance journalist Wouter Schutte who had asked for a deferment in 2021 and found that the amount he had to pay was too high.

“I thought I couldn’t be the only one,” he told RTL Nieuws, which started an investigation into the matter.

The tax office said the mistake was a result of “human error” when the software was adapted to accommodate a change in the way the interest was calculated in 2013.

People who had paid too much would get their money back before the end of this year, the department said. The amounts concerned range from between €18 and €200,000, RTL said.

Interest on late payments is used by the tax office as an encouragement to get private individuals and companies to pay their tax on time.

Among the people who were duped by the mistake are some 33,000 people who received benefits during the period, including parents hit by the child benefit scandal. Thousands of parents are still waiting for compensation.

The tax office is not the only government organisation to make mistakes. Benefits agency UWV recently admitted to thousands of errors in disability claims.

In a report out last year, national ombudsman Reinier van Zutphen said government organisations show little concern when it comes to compensating people who are victims of their own errors.