AI detects 20,000 hidden taxable swimming pools in France, netting €10m

Aerial photo scanning tool to be expanded to catch out other unreported home improvements

AI software has detected more than 20,000 secret private swimming pools in aerial photography, helping French tax officials bag about €10 million (£ 8.6 million) in extra property levies.

Home improvements, such as the addition of a loft or a pool, can boost the value of a property and increase the taxes homeowners pay in the Euro nation. A 30-square-metre pool, for example, could set you back an extra €200 (£170) a year. People are required to declare these kinds of constructions, though some keep quiet to avoid having to fork out more money. 

In a bid to catch tax dodgers out, nine departments working under France's tax office tested out machine-learning software to automatically find undeclared swimming pools from overhead photos. The software analyzed aerial images, scanning for telltale signs of pools such as blue rectangles in backyards. Officials used the code to identify homes with these pools, determined their address, and checked whether they have been reported or not by looking at a database.

The software has revealed 20,356 secret lagoons so far, amounting to €10 million in unpaid tax that French authorities can now extract. The program will be deployed across the whole country to scour for more unreported pools that could lead to an estimated €40 million (£34.1 million) in additional property taxes.

The software was developed by Google and Capgemini, and was reported to have a 30 per cent error rate in April. Arrays of solar panels could confuse the computer-vision software, causing it to flag false positives, and sometimes it would fail to detect swimming pools if they were bathed in shadows or covered by trees. The French Treasury said engineers were working to expand the application to look for different types of home modifications. 

"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, according to The Guardian.

Detecting hidden extensions or annexes jutting out of buildings is more difficult, however, and the software can't tell them apart from more benign objects, such as tents or tarpaulin. "This is our second stage of research and will also allow us to verify if a property is empty and should no longer be taxed," Magnant added. ®

PS: Wondering where the dollar conversion is? Don't worry, the Euro and US Dollar are just about on parity, so 10 million Euros is 10 million bucks.