Swimming pools, garages, sunrooms... how the tax authorities track you down

After targeting undeclared swimming pools, the tax authorities are now turning their attention to structures such as garages and sunrooms. To detect tax evaders, the authorities are using artificial intelligence to analyze aerial photos.

This new phase in the government’s plan to combat tax, social security, and customs fraud comes after 140,000 cases of tax evasion have already been detected since October 2021, generating 40 million euros in additional revenue for local governments, according to Thomas Cazenave, Minister of Public Accounts.

The detection system uses aerial photographs from the National Institute of Geographic Information (IGN) to identify unreported structures and require the owners in question to pay the local taxes they owe. However, detecting buildings is more difficult than detecting swimming pools, with an error rate of 55 to 60 percent for the algorithms, down from 90 percent at the outset, according to Olivier Villois, national secretary of the CGT Public Finance union.

Fortunately, a tax official is always responsible for verifying the information obtained through technology, ensuring that the structure is indeed subject to taxation and determining whether or not it has been reported. If an anomaly is detected, the tax authority asks the owner to provide an explanation or prove that the tax authority has made a mistake. Adjustments to the property tax—and the housing tax, in the case of a second home—apply only to the current year and do not apply retroactively to the past three years.