Retirement; Teachers' Retirement System of Oklahoma; dates; member; partial lump sum payments; certified athletic trainer; teaching experience; election or appointment; effective date.

HB 4331 updates Oklahoma's Teachers' Retirement System rules for current and future members. It clarifies that nonclassified staff hired after July 1, 2021 (working 20+ hours/week) can join the system, with a 30-day opt-out window after hiring; those who opt out lose future membership eligibility and prior service credit if rehired in classified roles. The bill also revises partial lump-sum payment rules, allowing retirees to receive a portion of their benefit as a lump sum (based on 12-36 months of payments) while reducing their monthly retirement amount, with the payment subject to IRS tax reporting and rollover options. These changes directly affect Oklahoma teachers, administrators, and certified athletic trainers participating in the system.