When do the annual French tax returns need to be declared?

For French residents the annual French tax returns usually need to be declared by the 31st May, however this is regional.

For Non-French residents, if under the Regime Simplifié the initial tax forms need to be submitted by the 1st week in  May with the additional forms to be declared by mid-May.

Under the Regime Micro-Entreprise the accounts need to be submitted by mid- May.