A member who is receiving military retirement pay based on 20 or more years of active duty with the armed forces shall be deemed to have received credit in a publicly supported retirement system for all service performed with the armed forces. Credit toward military retirement pay that is earned by a combination of active duty and nonactive duty with a reserve component of the armed forces and where the retirement pay is payable only upon the attainment of a specified age shall not be deemed credit in a publicly supported retirement system.