Judge: Tax authorities can keep details of algorithms secret

News June 3, 20252 minutesBart Reijmerink

ANP/Harold Versteeg

The tax authorities do not have to provide full disclosure about the algorithms used to check tax returns. That has the court in The Hague judged in a case brought by a journalist. The journalist had requested insight into how these digital controls work under the Open Government Act (Woo), but only received partial access. Much information remained black, including technical details, sources and locations of data collection.

Backgrounders

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According to the tax authorities, this is necessary to prevent abuse. In the defence, the tax authorities stated that malicious parties can use this information to change their behavior and thus stay under the radar. Knowledge of the servers and resources used would also make it easier for intruders to specifically break in. Some data sources would even be manipulable. That is why sensitive information remains out of the picture.

In the lawsuit, the journalist referred to the benefits scandal and other recent affairs, such as the police and DUO. He stated that there is a clear call in society for transparency around algorithmic government policy. According to him, the public interest in openness is greater than the interest of the tax authorities in keeping its control techniques secret. Especially to be able to check whether there is indirect discrimination or arbitrariness in the selection of reports.

The court acknowledged these concerns, but ruled that the importance of effective supervision by the tax authorities outweighs. In addition, it was emphasized that the tax authorities are indeed taking steps towards transparency. For example, dozens of documents have been made public, although partly unreadable. The judge states that protecting control methods and IT infrastructure is legitimate, precisely to ensure the integrity of the tax system.