Agreement of the parties
The employment contract is not immutable and must be adaptable according to the economic and organizational needs of the company. The employer cannot unilaterally modify the employment contract of an employee on an essential point, such as the salary or the activity rate. Just like the conclusion of the employment contract, any modification requires the agreement of both parties.
When the employer wishes to modify the employment contract to the detriment of the employee, he must use the mechanism of modification leave. The operation is twofold: the termination of the employment relationship is coupled with a proposal for a modified contract. A notice of termination must respect a certain number of formal elements to be valid.
The employee then has the choice of accepting the proposal and continuing the employment relationship under the new conditions or refusing and terminating the contract. If the employee refuses, the employment relationship is terminated at the end of the notice period. Be aware of the protection against termination at an inopportune juncture!
When the modification of the employment contract concerns all or part of the employees, the employer must be careful. He risks exposing himself to a situation of mass redundancy and having to set up a procedure of consultation of the personnel.
Entry into force
Unfavorable changes to the employment contract can only enter into force after a certain period of time has elapsed. The amendment of the contract may only affect the employee's future performance and not the performance already made.
Situations where the employer decides to modify the employment contract to the detriment of the employee without objective reasons are abusive. An employer who issues such a modification leave may have to pay compensation to the employee.
An employer may not propose changes to the employment contract that are contrary to mandatory provisions of the law, a collective employment contract or the Agreement on the Free Movement of Persons. Such a proposal is unlawful. In case of refusal, the employer is exposed to the risk of wrongful termination.