Mistakes made by state benefits agency UWV have been found to stretch back as far as 2006 duping many more people than thought, the AD reported on Monday.

Earlier the UWV confirmed that tens of thousands of people may have been given the wrong disability benefits (WIA) over several years. Benefits were routinely based on faulty indexation calculations of people’s wages, meaning many were getting less than they were entitled to. Others were getting too much.

The UWV subsequently announced a plan to review cases dating from between 2020 and 2024.

However, documents seen by the AD show that the mistakes date back as far as 2006 and that the agency has been aware of this since 2022.  A spokesman for the agency said it is unclear why it took 16 years to become aware of the flawed calculations.

The UWV has said the older cases will also be reviewed. Some 5% of all benefits claimants have been affected, the agency said. By its own estimate, the agency will have to review some 84,000 cases, 31,000 of which may not be dealt with at all because the recipients are either dead, retired or no longer entitled to the benefit.

The documents also show that the agency had been hesitant about going public about the mistakes and at one point even thought to cover them up.

“If you talk about trust in the government then this is another example of how not to achieve that,“ said lawyer Michiel Slot who handles claims against the UWV. “It is all about what is good for the organisation. But these are people who do not know they have been shortchanged and for whom that money would make a world of difference,” he told the paper.

An amount of €6.3 million has been mooted but, the AD said, that only covers the last five years and that other mistakes that may have been made will not be included in the review.

The operation still has to be approved by the government and it is also not clear if people who received too much money will have to pay it back.

The chaos around the WIA claims is the second major benefit scandal to hit the Netherlands. The process to compensate parents who were falsely accused by the tax office of fraudulently claiming child benefits between 2004 and 2019 is still ongoing.