Public retirement systems; Oklahoma Pension Legislation Actuarial Analysis Act; Oklahoma Public Employees Retirement System; defined contribution plan; defined benefit plan; effective dates.

HB 1879 modifies Oklahoma's public retirement systems by changing contribution rules and benefit calculations for state employees. It requires employees and employers to make specific contributions under defined benefit plans (guaranteed lifetime payments based on salary/history), while allowing employees to purchase additional service credit at actuarial cost to reach retirement eligibility. The bill also updates vesting rules for defined contribution accounts (like personal savings plans) and clarifies how service credit is calculated for retirement benefits. These changes directly affect current and future Oklahoma public employees enrolled in the Oklahoma Public Employees Retirement System.