There are six allowable actuarial cost methods under GASB 75. These methods are used in calculating the normal cost and the Actuarial Accrued Liability (AAL). Each method results in a different balance between current year and future year costs, and the method chosen may differ based on the circumstances of the employer.

The six actuarial methods used in determining OPEB liability are: entry age, frozen entry age, attained age, frozen attained age, unit credit, and aggregate.