| Premium Rate |  | |
Calculating your firm's premium rate
The premium rate your firm pays for workers' compensation insurance is based on the risk classifications assigned to your business and your firm's experience factor. The premium rates you pay, usually per hour worked, are determined by the following formula:
Premium Rate =
Firm's Experience Factor ×
(Class Accident Fund Base Rate + Class Medical Aid Fund Base Rate)
+ Supplemental Pension Fund Base Rate.
Example calculation
A firm is assigned to the Grading, Inspection Bureaus/Forestry risk class (1007) and the firm's experience factor is 0.9789. This risk class has the following hourly 2007 class base rates:
- Accident Fund: $0.4244.
- Medical Aid Fund: $0.2189.
- Supplemental Pension Fund: $0.0668.
The 2007 premium rate for this firm is:
0.9789 × ($0.4244 + $0.2189) + $0.0668 = $0.6965 per hour worked.
Sign up for the Claim & Account Center 
to view employer account and claims information such as premium rates, account balance and injured worker claim information.
Individual components of your premium rate
- Experience Rating
Learn about Your Firm's Experience Factor and how the rates for individual firms are determined. - Workers' Compensation Risk Classification
Learn about the risk classifications assigned to your business based on the nature of your business. - Base Rates
Learn about the three statewide base rates for each risk classification.
Additional information
- RCW 51.16.035 (www.leg.wa.gov) for the Accident and Medical Aid Fund rates.
- RCW 51.32.073 (www.leg.wa.gov) for the Supplemental Pension Fund rates.
