To calculate the contribution rates necessary to pre-fund the plan’s benefits, an actuary uses an actuarial cost method, asset valuation method, economic assumptions, and demographic assumptions. This section describes the actuarial assumptions we use in our valuation process. Please see
Actuarial Methods for descriptions of our actuarial cost and asset valuation methods. Please see the
Actuarial Methods and Assumptions section of the latest Actuarial Valuation Report for a list of frequently changing or new actuarial methods and assumptions.
Economic assumptions affect expectations regarding the accumulation of assets and the growth of projected pension benefits. In the valuation process, assumptions are required for four economic variables:
The Pension Funding Council (PFC) adopts economic assumptions for all plans/systems, except LEOFF 2 which are adopted by their Board; these assumptions are then subject to revision by the Legislature. The PFC and LEOFF 2 Board adopted lower economic assumptions in 2021. The investment rate of return assumption decreased from 7.50 percent (7.40 percent for LEOFF 2) to 7.00 percent; the general salary increase assumption decreased from 3.50 percent to 3.25 percent. These lower economic assumptions were first reflected in the 2021 AVR.
The economic assumptions used in the Actuarial Valuation Report are shown in the following table.
We use demographic assumptions to allow us to model the behavior of members over the next several years. These assumptions include rates of mortality, retirement, and termination. The demographic assumptions below were developed in the 2013-2018 Demographic Experience Study.
Mortality Rates Assumption
OSA developed rates of mortality for the retirement systems by taking the following steps.
These mortality rates vary by member status (eg, active, retiree, or survivor) and can be viewed by using the drop-down below. Please note these rates do not incorporate any mortality improvement or age offsets. The complete list of rates can be found in the Pub-2010 Public Retirement Plans Mortality Tables Report on the Society of Actuaries website. See the 2013-2018 Demographic Experience Study for more details regarding the development of these rates.
Select a table from the drop-down below:
Active and Terminated Vested Mortality Rates
Retiree Mortality Rates
Members with Disabilities Mortality Rates
Survivor Mortality Rates
Probability of Service Retirement
Probability of Service Retirement (Plans 1 and Public Safety)
Probability of Service Retirement (Plans 2/3)
Termination Rates Assumption
Our termination rates assumption is subdivided based on whether the member is retirement-eligible. For retirement-eligible members who terminate, we assume they are delaying commencement of their retirement benefit until they are eligible to receive an unreduced benefit.
Disability Rates Assumption
Service-Based Salary Increase Assumption
Other Demographic Assumptions
In addition to the five demographic assumptions mentioned above, we also study a number of other assumptions such as the probability that a member who leaves employment withdraws their contribution and the probability that a member’s death is duty-related. For a list of these other assumptions and information pertaining to them, please see our 2013-2018 Demographic Experience Study webpage.
We include the following miscellaneous assumptions and methods in this valuation.
Last Reviewed: 08/21/2023
Last Updated: 08/21/2023