Your pension is governed by state law and protected by the State Constitution. Whenever the State Legislature made substantial changes in public employee pensions, it passed a new law creating a new plan for people hired after the law’s effective date. So public employees fall into different pension plans depending on when they began their service.
The plans may have different costs and benefits, so to find out about your pension plan, you need to know what tier you are in. In some cases, people are permitted to change tiers or to transfer their tier membership from another eligible retirement system.