When a tenant gives his owner leave and wishes to benefit from a reduced period of notice (professional transfer, loss of job, housing located in tense zone...), he must justify it at the time of sending the letter of leave. A justification given late is not valid. Otherwise, the period of notice applicable to such leave shall be 3 months. This is what the Court of Cassation ruled in its decision of April 11, 2019.
A tenant gives his landlord his leave, then in a second time, the proof giving him the right to a reduced notice to 1 month. The owner refuses the reduced notice because of the late submission of the proof. For him, the period of notice to be applied is 3 months. Not for the Court of Appeal which considers that the notification of leave with a period of notice of 1 month cannot be challenged.
However, the Court of Cassation recalls that the obligation to justify a reduced notice is done when sending the letter of leave. In the absence of proof at the same time as the leave, the period to be applied is 3 months.