How is a workers' comp premium calculated?

The base formula is payroll divided by 100, multiplied by the class code rate, multiplied by the experience modifier. So 500,000 dollars of payroll at a 1.50 rate with a 1.00 mod equals 7,500 dollars in base premium before any credits.

What is an experience modifier?

The experience modification factor compares your business's claims history to others in your industry. A mod above 1.00 raises your premium because your losses are worse than average; below 1.00 lowers it because your safety record is better.

Where do I find my class code rate?

Class codes and their loss-cost rates come from the Wisconsin Compensation Rating Bureau (WCRB), which administers rating in Wisconsin. Your insurance agent or policy declarations page lists the exact rate for each job classification.

Is workers' comp insurance mandatory in Wisconsin?

Yes. Wisconsin generally requires employers with three or more employees, or one or more employees earning 500 dollars or more in a quarter, to carry workers' compensation coverage. Coverage is bought through private carriers in Wisconsin.

Does this include taxes and assessment fees?

This tool estimates the manual premium from rate, payroll and your experience modifier. Wisconsin policies can also carry small assessment surcharges and expense constants that vary by carrier and are not included here.

Wisconsin Workers' Compensation Premium Calculator

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Workers’ compensation premiums are built from a simple but multiplicative formula, and small changes in your class code rate or experience modifier can move the bill substantially. This calculator estimates an employer’s annual Wisconsin workers’ comp premium from payroll, the class code base rate and the experience modifier, with room for schedule credits or surcharges.

How it works

The standard manual-premium formula used across the United States, including Wisconsin, is:

premium = (annual payroll ÷ 100) × class rate × experience mod

Each piece matters:

Payroll ÷ 100. Rates are quoted per $100 of payroll, so payroll is divided by 100 first.
Class code rate. Set by the Wisconsin Compensation Rating Bureau for each job classification — clerical work is cheap, roofing is expensive.
Experience modifier. A factor reflecting your claims history. 1.00 is average; below cuts premium, above raises it.

After the base premium, the calculator applies any schedule credit or surcharge you enter as a percentage, which carriers use to reward (or penalize) specific risk factors.

Tips and example

A landscaping firm with $400,000 in payroll, a class rate of $2.80 and a mod of 0.95 would estimate (400000 ÷ 100) × 2.80 × 0.95 = $10,640. Lowering the experience mod through better safety performance is the single biggest lever an employer controls. This is a manual-premium estimate; final Wisconsin policies may add expense constants and small statutory assessments set by your carrier.