Departmental elections take place on the same day as the regional ones. The voters concerned will therefore vote twice, for each of the ballots.
The ballot is binomial, that is to say that in each canton, a man and a woman are elected at the same time, as well as their replacements.
The two-round majority voting system. To be elected in the first round, a pair must obtain the absolute majority of votes cast, and at least a quarter of those registered.
To qualify for the second round, a pair must obtain more than 12.5% of the registrants. Exceptions: if no pair reaches this threshold or if only one does, the two leading compete in the second round.
There are no departmental elections in Paris and in the metropolis of Lyon, in single territorial collectivities assimilated to a region (Corsica, Martinique, Guyana), as well as in overseas collectivities with special status. On the other hand, there are departmental elections in Mayotte, a single territorial community comparable to a department.