Firstly, remember to include a resolutory clause in your lease which will allow you to enforce it even if the lease has not yet expired.
Legal proceedings for the recovery of unpaid rent begin with the delivery of an order to pay via a huissier de justice.
Following the order, the tenant has two months to pay the outstanding rent or to establish a payment agreement. Failing that, a hearing in the district court (tribunal d’instance) will be set.
This is followed by different options leading to a seizure proceedings with the aim of recovering the unpaid rent, and/or eviction proceedings in order to evict the tenant and reclaim your property.