For purposes of complying with federal Internal Revenue Service rules and regulations, the plan year for this retirement system shall be the 12 month period beginning on July 1 of each year. (Code 1981, § 47-6-25, enacted by Ga. L. 2009, p. 947, § 25/HB 202.) Effective date. — This Code section became effective May 11, 2009. ARTICLE 3 MEMBERSHIP IN THE RETIREMENT SYSTEM