If you rent out your gites or chambres d'hotes, it is a legal obligation to notify the Mairie of your village, town or city through the forms here below.
For every mutation you must renew your notification.

Meublés de Tourisme (PDF)
Chambres d'Hôtes (PDF)

If you do not do this, then this can be fined with 450 euros. There is an increasing control.
On rental income you have to pay tax.