Last updated: March 2026

Workers compensation insurance for employers

Workers comp costs more than it should for most employers. The premium you pay isn't just based on your industry and headcount. It's calculated from your payroll dollars, your class code assignments, and your experience modification rate, and most employers have never seen the actual math behind their bill. I've reviewed workers comp policies for employers in 30+ industries over my career, and the pattern is consistent: the first quote is accepted without question, the class codes are assigned by the broker without verification, and the annual audit produces a surprise bill that nobody budgeted for.

What workers comp covers and what it costs

Workers compensation insurance covers medical expenses, lost wages, and rehabilitation costs when an employee is injured on the job. It also protects the employer from lawsuits related to workplace injuries. Every state except Texas requires it, though the trigger point varies. Some states require coverage with your first employee. Others don't mandate it until you reach three or five employees. Ohio, North Dakota, Washington, and Wyoming operate monopolistic state funds where you must buy coverage from the state rather than a private insurer.

Workers comp cost per employee depends almost entirely on what those employees do. Office workers (class code 8810) cost $0.20 to $0.50 per $100 of payroll. A retail operation runs $1.00 to $2.50. Construction trades range from $5.00 to $20.00+ per $100 of payroll depending on the specific trade. Class code assignments follow the NCCI classification system in most states. For a small business with 10 office employees earning $50,000 each, workers comp runs $1,000 to $2,500 per year. The same headcount in construction roofing could cost $50,000 to $100,000. The tradeoff with workers comp for small business is always between getting the cheapest quote and getting the right class codes. A cheaper rate on the wrong class code costs more at audit than the higher rate would have cost all year.

How your premium is calculated

The formula is straightforward: payroll dollars ÷ 100 × class code rate × experience modification rate = annual premium. A plumbing contractor with $500,000 in payroll, a class code rate of $4.50 per $100, and an EMR of 1.10 pays $500,000 ÷ 100 × $4.50 × 1.10 = $24,750 per year. Change that EMR to 0.85 through three clean years and the same payroll costs $19,125. Change it to 1.35 after a bad claim and it jumps to $30,375. Same employees, same work, same payroll. The EMR alone creates an $11,250 spread.

The EMR is the most expensive number most employers have never looked up.

When this is wrong: employers in monopolistic fund states (Ohio, North Dakota, Washington, Wyoming) where the premium formula includes state-specific surcharges and assessment factors that modify the base calculation. The core formula still applies, but the multipliers are different and not negotiable.

Your experience modification rate multiplies your base premium for three years after a claim. One $15,000 claim can increase your premium by 20% to 40% across those three years, which often costs the employer more than the claim itself. The EMR calculation uses your actual losses compared to expected losses for your industry and size. Smaller employers get punished harder because a single claim represents a larger percentage of their expected loss pool. I've seen a $9,000 slip-and-fall claim add $22,000 in premium over three years for a 15-employee restaurant.

A single small claim can cost more in premium increases than the claim itself paid out.

When this advice fails: new businesses in their first three years that do not yet have enough loss history to generate an EMR. Until you qualify for an experience rating (which requires meeting your state's premium volume threshold), your premium is based on the manual rate alone. The EMR multiplier does not apply, which means one early claim will not increase your premium until the rating catches up.

Workers comp and payroll are the same math

This is the angle that insurance brokers and insurance comparison sites miss entirely. Workers comp premium is based on payroll. Workers comp class codes are based on job duties reported through payroll. The annual workers comp audit compares your actual payroll to the estimated payroll you gave at policy inception. The same gross pay figures your provider calculates using IRS Publication 15 withholding tables are the figures the workers comp auditor uses as the starting point for your premium. If your payroll grew 20% and you didn't report it, you owe 20% more premium at audit plus the audit fee. If your payroll provider assigns job classifications differently than your workers comp policy, the auditor will reclassify employees at the higher rate retroactively.

Workers comp for contractors creates a specific problem. A general contractor requires every sub to carry their own workers comp policy. If the sub doesn't have one, the GC's policy covers the sub's employees and the GC pays the premium. A ghost policy exists specifically for this situation. It costs $500 to $1,200 per year, covers zero employees, and provides the certificate of insurance the GC requires. Workers comp for 1099 contractors follows the same logic: if your 1099 workers don't carry their own coverage, your insurer may add them to your policy and bill you at audit.

An uninsured sub's entire invoice becomes auditable payroll on the GC's workers comp policy.

When this recommendation changes: states like Texas where workers comp is not mandatory and the GC's contract may allow subs to opt out entirely. In that case, the GC still carries liability risk for an uninsured sub's injury, but the premium audit mechanism works differently because the mandate is contractual rather than statutory.

Guides by topic

Ghost policy guide explains who needs one, what it costs, and how to get a workers comp certificate without employees. Pay as you go workers comp ties your premium to actual payroll instead of estimates, which eliminates the audit surprise at year end. The tradeoff is a slightly higher rate per dollar of payroll in exchange for never writing a large catch-up check.

Workers comp audit guide covers what the auditor looks for, how to prepare, and how to dispute a reclassification. Workers comp vs general liability answers the question employers ask constantly, and the answer matters because they cover completely different risks. Do I need workers comp walks through the state-by-state requirements for sole proprietors, LLCs, and small employers at the one-to-five employee threshold.

Construction employers deal with workers comp class code complexity more than anyone because a single crew can span three or four codes on the same project. Getting those splits right on payroll is the only way to get them right on the workers comp audit.

Written by a Certified Payroll Professional with 30 years of experience.

This is not legal or financial advice. Consult a qualified professional for your specific situation.