How long does planning permission last?

Once you have obtained a permis de construire it is valid for three years from the date of being given formal permission (a law come in last year extending this from two). This also applies to the more informal déclaration préalable de travaux that is required for certain minor constructions, as well as certain other permissions like a permis à démolir (demolition permit), or permis d’aménager.

The duration may on request be extended twice by one year each time, however only if the rules applicable to your project have not changed in the meantime. In other cases the permission runs out after the three years.