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 + Class Stay At Work Base Rate)
+ Supplemental Pension Fund Base Rate.

Example calculation

A firm is assigned to the Clerical Office, Not Otherwise Classified risk class (4904—00) and the firm's experience factor is 0.9789. This risk class has the following hourly 2012 class base rates:

• Accident Fund: $0.0336
• Medical Aid Fund: $0.0223
• Stay At Work: $0.0007
• Supplemental Pension Fund: $0.0932

The 2012 premium rate for this firm is:
0.9789 × ($0.0336 + $0.0223 + 0.0007) + $0.0932 = $0.1486 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.
• Base Rates
  Learn about the four statewide base rates for each risk classification.

Additional information

• RCW 51.16.035 (www.leg.wa.gov) for the Accident, Stay at Work, and Medical Aid Fund rates.
• RCW 51.32.073 (www.leg.wa.gov) for the Supplemental Pension Fund rates.