21. If the application to redeem a leave without pay authorized by the employer and defined in section 20 is not received within six months following the return to work, in the case of a full-time leave without pay, or within six months following the end of the authorized leave, in the case of a part-time leave without pay, the amount required to pay the redemption costs bears interest at the rate in force pursuant to the Act respecting the Government and Public Employees Retirement Plan (chapter R-10) on the date of receipt of the application. The interest is computed from the end of the sixth month following the return to work or, in the case of a part-time leave without pay, from the end of the sixth month following the end of the authorized leave until the date of receipt of the application, and is compounded annually.
The employee may, to pay the redemption costs of a period of leave without pay, spread payment thereof over such period and at such intervals as may be determined by the Commission.