The development tax base is made up of:
1° The product of the surface area of the building by the value per square metre of this surface area, set at a flat rate of €885 for municipalities outside the Ile-de-France region and €1,003 for municipalities within the Ile-de-France region.
The surface area of the building is the sum of the floor areas of each enclosed and covered level, calculated on the basis of the inner surface of the building’s facades in accordance with the conditions defined by decree.
The values per square metre are updated annually.
The values per square metre are updated on 1st January each year in line with the latest construction cost index published by the French National Institute for Statistics and Economic Studies. Where applicable, values are rounded down to the nearest euro;
> The value of fittings and fixtures and fittings is calculated on a per square metre basis.
2° The value of fixtures and fittings, set on a flat-rate basis under the conditions set out in Article 1635 quater J.