Dear Priyanka,
Resignation,per se, is the action initiated by an employee for unilateral termination of his/her contract of employment. Therefore, it is always governed by the terms of exit such as period of notice or any alternative thereof, repayment of the unpaid loans and advances, if any obtained from the employer, return of property of the employer entrusted to with the employee etc., as specifically stated in the contract of employment. Even otherwise, formal acceptance of resignation by the employer is an implied procedure in the realm of employment to give effect to resignation. However, acceptance of resignation is a rule whereas rejection is only an exception in situations like the inevitable requirement of the services of the employee in an important work, pendency of any disciplinary proceedings against the employee. Again the resignation may be immediate or prospective. In the case of prospective resignation, it becomes effective ony on the date from which the employee chooses to quit. Since employment is basically a contract of service, the employer should remember always that he has no absolute discretion or inherent right to compel an unwilling employee to continue his services in the organisation.Therefore, how much reasonable time an employer can take to accept the resignation can not be generally determined with any precision.