French property tax fraud: what is targeted other than 'secret’ swimming pools?

The AI-assisted technology designed to detect undeclared swimming pools is being widened to focus on other structures too

Swimming pools are not the only ‘secret’ structures that are checked
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More than 140,000 taxpayers in France were found to have ‘undeclared’ swimming pools in 2023, in many cases being ordered to pay extra taxe foncière, figures show, as authorities step up their checks on other structures.

La Direction générale des finances publiques (DGFiP) said its checks on undeclared swimming pools had raised €40 million extra in taxe foncière taxes last year. 

Aerial photos and AI

Authorities have increased checks on swimming pools in particular over the past few years, and have worked with Google and consulting cabinet Capgemini.

The system uses aerial photographs taken by the Institut national de l'information géographique et forestière. It then cross references these photos with taxpayer data, using AI, to detect people who have not properly declared the state of their property.

If the AI system detects a possible anomaly, the report is checked by a human, and if correct, a letter is sent to the property owner to inform them that more tax is due.

Read also: How French tax authorities are tracking undeclared swimming pools 
Read also: Tax authorities discover 120,000 undeclared swimming pools in France 

The artificial intelligence system has been in place since 2022, when it was tested in nine departments and found 20,000 undeclared swimming pools as a result (netting €10 million extra in taxes).

Authorities have been working to improve their detection abilities since October 2021, as part of its ‘Innovative Foncier’ project.

Read also: Swimming pools: How to check you are within tax rules in France 

Beyond swimming pools

Swimming pools are not the only ‘secret’ structures that are checked, though they were the main focus last year. The DGFiP says it will now be stepping up the search for other undeclared improvements to properties, which may include, for example: 

  • House extensions

  • Large garden sheds

  • Conservatories 

Note that such improvements are also often subject to a one-off taxe d’aménagement on completion, which may also not have been paid if the work was not declared to the tax authorities.

Having said that, the DGFiP’s latest report did not mention it sought to recover this. 

Read also: New shed, veranda, pool: how to declare in France and what time frame 
Read more: What changes require you to make new property declaration in France?

What is taxe foncière and who pays it? 

Taxe foncière must be paid on main homes and second homes, unlike taxe d'habitation, which now only applies to second homes. Barring any exemptions, taxe foncière is due if you owned French property on January 1 of a given year.

It is payable whether a property is furnished/used or not. However, there are several reductions or exemptions that may apply, linked to factors such as age, disability or income.

Read more: Taxe foncière explainer: Who pays and the exemptions

For example, one of the exemptions, for main homes only, concerns older people who receive the French pension top-up benefit ASPA or who are recipients of the Allocation supplémentaire d’invalidité (ASI).

Extensions to your property, such as verandas, conservatories and additional bedrooms need to be declared. External installations including garden sheds and swimming pools, most pergolas and garden shelters are also included.

In short, any work that requires either a permis de construire or déclaration préalable de travaux likely needs to be declared.

If you have any queries, you can contact your mairie to confirm. 

How do I declare new structures, and when? 

The additions need to be declared through your personal space on the French tax site, via the Biens immobiliers (property) section.

The deadline for informing authorities of the extension or installation is tied to the construction of the project. You must do this within 90 days of the end of construction.

Read more: ‘Garden shed’ tax in France: what rises in 2024 and what exemptions?

You can find out more information on the Service Public site here.