Washington State determines workers' compensation premiums by applying a rate to the employer's average monthly wage (AMW), which is the average of the employee's wages over the most recent 13‑week period, capped at the state's statutory maximum. For 2024 the AMW ceiling is $13,500 per month, and the standard rate for most non‑hazardous occupations is 1.10% of that wage, resulting in a typical monthly premium of about $148.50 per employee. Rates vary by industry risk classification, with high‑risk sectors such as construction reaching up to 4.45% of the AMW.
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How the Average Monthly Wage Is Calculated
The AMW is not a fixed state‑wide figure; it reflects each worker's actual earnings. Employers sum the employee's wages for the latest 13 weeks, divide by 13, and then apply the applicable rate. If the calculated wage exceeds the $13,500 cap, the premium is based on the cap instead of the actual earnings.
Standard Workers' Compensation Rate Schedule
Washington's Department of Labor & Industries (L&I) publishes a rate schedule that groups occupations into risk classes. Below is a snapshot of common classes and their 2024 rates:
| Risk Class | Industry Example | Rate (% of AMW) |
|---|---|---|
| Class 1 | Clerical/Administrative | 0.75 |
| Class 2 | Retail Sales | 1.10 |
| Class 3 | Manufacturing (general) | 2.25 |
| Class 4 | Construction (light) | 3.30 |
| Class 5 | Construction (heavy) | 4.45 |
Impact of Wage Caps on Premiums
When an employee's actual monthly wage exceeds $13,500, the premium is limited to the cap. For example, an employee earning $20,000 per month in a 1.10% class would still pay $148.50 (1.10% of $13,500) rather than $220. This ceiling protects high‑earning workers from disproportionately high premiums while ensuring the state's compensation fund remains funded.
Adjustments and Experience Modifiers
Employers with a safe‑record may qualify for an experience modifier, reducing their effective rate by up to 30%. Conversely, a history of claims can increase the modifier, raising the premium. Modifiers are recalculated annually and applied to the base rate before multiplying by the AMW.
Key Compliance Checklist for Employers
- Verify each employee's 13‑week wage data quarterly.
- Confirm the correct risk class for every role.
- Monitor the $13,500 wage cap to avoid over‑paying.
- Track claim history to manage experience modifiers.
- Submit premium payments to L&I by the quarterly deadline.
Where to Find Updated Rates and Resources
The Washington State L&I website publishes the official rate tables each July and provides calculators for estimating premiums. Employers can also contact L&I's Employer Services Center for assistance in classification or dispute resolution.