A member on leave of absence receiving temporary workers’ compensation payments and a reduced salary or no salary from the employer who is entitled to allowable service credit for the period of absence under section 352B.011, subdivision 3, paragraph (b), may make payment to the fund for the difference between salary received, if any, and the salary that the member would normally receive if the member was not on leave of absence during the period. The member shall pay an amount equal to the member and employer contribution rate under section 352B.02, subdivisions 1b and 1c, on the differential salary amount for the period of the leave of absence. The employing department, at its option, may pay the employer amount on behalf of the member. Payment made under this subdivision must include interest at the applicable annual rate or rates specified in section 356.59, subdivision 2, and must be completed within one year of the member’s return from the leave of absence.