Workers' Comp Audit Bill Estimator
Rebuild your audited premium from your own numbers and see why it's different from what you paid up front. Free, private, nothing to sign up for.
Simplified estimate: payroll by class × rate ÷ 100 × experience mod, plus any credits or fees you enter, compared with your deposit premium. Your carrier's calculation may include factors not shown here.
How the math works
Workers' comp is priced per $100 of payroll. For each class code on your policy, the basic premium is payroll ÷ 100 × rate. Add the classes together and multiply by your experience mod, then other credits, discounts, and fees on your policy apply. At the start of the year your carrier runs that formula on estimated payroll and bills you a deposit. After the policy ends, the premium audit runs it again on your actual payroll and records. The difference is either an additional premium bill or a refund.
The rates and factors on your policy generally carry over to the final audit. So if the invoice is much bigger than this estimate, the payroll inputs are usually what changed: payroll was higher, it moved to a more expensive class, or the auditor added payroll for subcontractors.
If the gap doesn't make sense
- Subs without certificates? Run the Uninsured Subcontractor Calculator. This is often the biggest unexplained line on contractor audits.
- A class you don't recognize? Ask the auditor in writing why payroll was placed there. Payroll generally can't be split across classes by estimate or percentage; it takes payroll records kept by class.
- Lots of overtime? In many states the extra "premium" part of overtime can be excluded if your records show it separately. See why audit bills run high.
- Ready to push back? Follow our step-by-step dispute guide and use the dispute letter template.
Frequently asked questions
Where do I find my class codes and rates?
On your policy's declarations or information page, usually in a table listing each class code, estimated payroll, and rate per $100 of payroll. Your audit worksheet should list the same classes with audited payroll.
What is an experience mod?
An experience modification factor adjusts your premium up or down based on your past claims compared with similar businesses. 1.00 is neutral; above 1.00 raises premium, below lowers it. It appears on your policy. If you don't have one, leave it at 1.00.
Why doesn't my estimate match my invoice exactly?
Carriers apply factors in a defined order and may include items this tool doesn't model, such as premium discounts that change with audited premium size, minimum premium, state assessments, or charges for uninsured subcontractors. Enter known credits and fees in the adjustment fields to get closer, and ask your carrier for the full audit worksheet to compare line by line.
Does this tool store my numbers?
No. Everything is calculated in your browser. Nothing you type into the calculator is sent to us.
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