French tax officials use AI to spot 20,000 undeclared pools

French tax authorities using AI software have found thousands of undeclared private swimming pools, landing the owners with bills totalling about ¤10m.

The system, developed by Google and Capgemini, can identify pools on aerial images and cross-checks them with land registry databases. Launched as an experiment a year ago in nine French departments, it has uncovered 20,356 pools, the tax office said on Monday, and will be extended across the country.

Modifications to property, including adding swimming pools, must be declared to the tax office within 90 days of completion. As property taxes are based on the rental value of the property, improvements mean an increase in taxes. A typical pool of 30 sq metres would be taxed at about an extra ¤200 a year.

In April it was claimed that the Google-Capgemini software had a 30% margin of error. Not only was it mistaking solar panels for swimming pools, but it was failing to pick up taxable extensions hidden under trees or in the shadows of a property. Tests are being carried out to perfect the technology.

France is believed to have about 3.2m private swimming pools and reported a boom even before the Covid lockdowns of 2020 and 2021, when there was a surge in installations as more people worked from home.

The public finance authority DGFiP said the AI programme would now be rolled out nationwide, potentially leading to ¤40m in new taxes on private pools in 2023.

The clampdown comes as French environmentalists have called for the banning of private pools after the summer heatwave sparked drought and water restrictions.