In the building sector, there are certain works that can benefit from a reduced rate of TVA of 10% and 5.5%. In order for these rates to be granted to your customers, an attestation de TVA must be completed and given to you, the tradesperson. As a result, your clients can save money on their projects: construction and renovation.
The reduced rate of 10% TVA applies to improvement, transformation, and maintenance work
The reduced rate of 5.5% TVA applies to energy renovation work [supply, installation, maintenance]
If the work does not involve any of these 2 cited examples, or if the premises are less than 2 years old the artisan must apply the normal rate of TVA 20%
For work less than 300€ the TVA attestation is not required.
Any tradesperson who is not registered for TVA MUST not be adding 20% or any variation of TVA to their devis. TVA is money collected for the government.
A copy of the attestation must accompany your client file and be available in the event of an audit.
This is a quick version of what the Cerfa is and for further reading and understanding of your responsibility as a Tradesperson here are some useful links
Download attestation here https://www.impots.gouv.fr/sites/default/files/formulaires/1301-sd/2016/1301-sd_1515.pdf
You might also like to read: Selling a Second Property In France: Restrictions on Offsetting Costs of Works and Improvements