Understanding How Workers' Compensation Rates Are Calculated

Core Formula for Workers' Compensation Rates

Workers' compensation rates are calculated by multiplying an employer's total payroll by a classification-specific rate per $100 of payroll, then adjusting for experience modifiers and state premiums.

Key Components of the Calculation

Payroll: The total wages paid to employees in each job classification, reported in $100 units.

Classification Codes: Each occupation is assigned a class code with a base rate reflecting the inherent risk of the work.

Experience Modifier (E‑Mod): A factor that raises or lowers the rate based on the employer's claim history compared to industry averages.

State Factors: States may add surcharge or discount percentages, and some impose minimum premium floors.

Typical Calculation Steps

1. Identify each job's classification code.2. Multiply the payroll for that classification by the base rate (per $100).3. Apply the experience modifier to the subtotal.4. Add any state‑specific surcharges or discounts.5. Sum across all classifications for the total premium.

Comparison of Influencing Factors

Why Rates Vary Between Employers

Even with identical classifications, rates differ because the experience modifier reflects each employer's safety record, and state regulations differ in required minimums and additional assessments.