A distinction must be made between “changes to the conditions of employment” which the employer may decide unilaterally (hours, leave, etc.) and “modification of the employment contract”, which requires the agreement of the worker and which relate to: characterized by the fact that they do not have a defined duration, a contract of indefinite duration may be terminated at the request of one of the parties (dismissal, resignation, retirement …), by appointment between the parties or for reasons of force majeure. An employment contract is an agreement that governs an employment relationship where by which a person undertakes to work under another person for remuneration. An exception to this rule would be that the worker has accepted the amendment beforehand, for example a mobility clause or a non-performance clause. The employer must inform the worker of the change. The worker`s non-response is a tacit agreement.