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

theguardian.com:

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.

The tax office – or le fisc, as it is known – says it is now looking at using the system to spot undeclared annexes, extensions and verandas including permanent pergolas.

“We are particularly targeting house extensions like verandas, but we have to be sure that the software can find buildings with a large footprint and not the dog kennel or the children’s playhouse,” Antoine Magnant, the deputy director general of public finances, told Le Parisien newspaper.

However, the tax authorities’ technical team say they are not yet able to establish whether a rectangular shape on an aerial image is an extension or a tent, terrace or even tarpaulin placed on the ground.

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.

“This is our second stage