Workers’ comp is one of the few insurance costs calculated by a real formula — which means once you understand the formula, you understand your bill and how to lower it. Here’s how carriers actually price it.
The formula
At its core: (class code rate × every $100 of payroll) × experience mod, plus state fees and any credits or debits. Three inputs decide almost everything — your classification, your payroll, and your claims history.
1. Class codes — what work your team does
Every job type has a class code with a rate reflecting that work’s injury history. Clerical staff cost pennies per $100 of payroll; roofing costs dollars. Misclassification is the single most common reason businesses overpay — an office manager rated as field labor, or a mixed operation lumped under its most expensive class.
2. Payroll — the exposure base
Premiums scale with payroll, which means your quote is built on estimates and trued up at a year-end premium audit. Estimate too low and you get a surprise bill; too high and you’ve loaned the carrier your money. (This is exactly the problem pay-as-you-go workers comp solves — premiums calculated from actual payroll every pay period.)
3. Experience mod — your track record
The experience modification factor compares your claims to similar businesses. Start at 1.0; fewer claims earn a discount below 1.0, more claims cost you above it. It follows your business for years, which is why claim prevention is a financial strategy, not just a safety one.
How to pay less
- Verify every class code — especially office staff, supervisors, and mixed-duty employees
- Give accurate payroll estimates, or switch to pay-as-you-go billing and skip the estimating game
- Compare multiple A-rated carriers — rates and schedule credits vary more than most owners expect
- Report claims promptly and use return-to-work programs to keep your mod down
- Keep certificates from subcontractors so their payroll isn’t charged to you at audit
Frequently asked questions
Is workers’ comp required?
In most states, yes — often from your very first employee. Requirements vary by state and industry; see our FAQ page or ask us about your state.
Does workers’ comp cover owners?
Owners can usually choose to be included or excluded. Excluding yourself lowers premium but leaves your own injuries uncovered — and some client contracts require owner coverage.
Why did my premium change at audit?
The audit reconciles estimated payroll against actual. Big swings mean the original estimate was off — accurate estimates or pay-as-you-go billing prevent the surprise.
The fastest way to know your real number: compare quotes from multiple A-rated carriers — it takes a few minutes.
Contractors: your trade and state change the comp math more than any other factor — see state-by-state licensing and insurance details at our contractor insurance site.
In New Jersey, rates are administered through NJCRIB — see our full New Jersey workers’ comp guide for what actually moves premiums in the Garden State.
Dig into the codes that set your rate in our class code guides, and see the full savings playbook in how to lower your workers’ comp premium.