If a member for whose absence on military service employer’s contributions are paid or payable under Section 20997 withdraws or has withdrawn or is or has been paid his or her accumulated contributions after his or her return to state service from military service, and thereafter reenters or reentered state service without redepositing the amount of the accumulated contributions last withdrawn by or repaid to him or her, he or she is nevertheless entitled to be credited with the employer’s contributions for his or her absence on military service under Section 20997, and to receive credit for service for the period of his or her absence on military service, the same as if he or she had not withdrawn or been repaid his or her accumulated contributions. The future contribution rate of a member shall be based upon an age determined by deducting the period of his or her absence on military service so credited to him or her from his age at the time of his or her last re-entry into state service.