List: these are the French home improvement works that must be declared
Inform tax authorities separately even if you have construction permit
Constructions such as conservatories must be declared within 90 days of completion
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Spring is often seen as an excellent time to begin work on your property, as the warmer weather means more time spent outside.
Large projects – such as the installation of a swimming pool – may also be started, to have them ready in time for summer.
However, did you know that many of these projects need to be declared to the tax authorities within 90 days of being completed, and can be subject to tax?
This is the case even though the projects need prior approval from the local mairie, via a permis de construire, permis d'aménager or a déclaration préalable de travaux.
The tax is known as the taxe d’aménagement – often called the garden shed or ‘development’ tax.
This tax may also increase the property’s current taxe foncière (property tax) due to the expected increased value of the property from the works.
When does the tax apply?
The tax applies to constructions and improvements that require one of the declarations above, reach a size of 5m² or more and have a height of 1.80m.
The construction must also be enclosed, for example, a pergola is not applicable for the tax if it is not walled or roofed.
Extensions that are applicable – providing the criteria is met – include:
However, it is also required for certain other extensions of a large size even if they do not reach fulfil the specifications above:
Swimming pools
Carports
Wind turbines
Solar panels
Greenhouses
Changes that do not fall into these categories, such as aesthetic works (repainting of walls, etc, the construction of fences, or necessary changes such as the installation of a septic tank) are not applicable for this tax.
How do I declare the changes?
Once the construction is complete, it must be declared to tax authorities within 90 days.
This can be done online via the biens immobiliers section of your personal space on the French tax site.
You can also declare using a physical form which can be found here.
Note there is a longer declaration period of up to seven months after the authorisation is issued for extensions with a surface area of over 5,000m².
The amount of tax required is calculated based on a number of factors including size of the extension, with increases added at local levels.
Several extensions have their own specific calculations, which you can find on the official service Public website.
The tax is paid either in one tranche or in installments, depending on the overall value.
The level of the tax increased in 2025.
More information on the tax rates – and penalties for non-compliance – can be found in our article below.
Read more: France's ‘garden shed tax’ sees 2025 rise, find new rates below
