Once a member has filed an application for benefits and chosen an option, including a single life annuity, the option shall be deemed to be irrevocable except as otherwise provided in section 5907(j) of the code (relating to rights and duties of State employees and members) or unless an annuitant returns to service for a period not less than 6 months and subsequently retires with recomputation of benefits.
4 Pa. Code § 247.5