Why is my workers comp being audited, and what will it cost me?
Because the premium you paid was an estimate and the audit settles it. Workers compensation is rated on payroll you projected at the start of the term, and at the end the carrier checks what the payroll actually was. If you grew, you owe the difference. The bills that shock people are almost never the growth — they are uninsured subcontractors added to your payroll, or an estimate nobody has updated in years.
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What this means for you
- YOU ARE RATED ON AN ESTIMATE, ALWAYS. Every workers compensation policy starts as a projection of payroll by class code. Nobody knows next year’s payroll, so the policy prices a guess and the audit trues it up. A bill at audit is not a penalty, it is the invoice for coverage you already had and had not paid for.
- UNINSURED SUBCONTRACTORS ARE THE BIG ONE. If you cannot produce a certificate of insurance for a subcontractor, most states let the auditor treat what you paid them as your payroll, at your class rate. A single six-month sub with no certificate can add more to an audit than a year of ordinary growth. Collecting certificates is the cheapest premium control that exists, and it has to happen when they start, not when the auditor asks.
- A STALE ESTIMATE COMPOUNDS. If nobody revises the projected payroll at renewal, a growing business is underpriced every year and audited every year, and the bills get larger as the gap widens. That is a broker’s job. We have taken over accounts where the same figure had been re-used for three straight renewals and the client believed the carrier was gouging them.
- CLASS CODES DECIDE THE RATE, AND ONE WRONG CODE COSTS MORE THAN THE GROWTH. If clerical staff are being rated at the field rate, or a whole crew is coded to the highest-hazard class because that is what the policy says the business does, the audit applies that error to a full year of real payroll. Check the codes before the audit rather than arguing them afterwards.
- SOME PAYROLL IS NOT COUNTED IN FULL. Most states exclude the premium portion of overtime, so ten hours at time-and-a-half counts as ten hours at straight time — but only if your records separate it. Records that lump it together get audited on the whole figure, which is money given away for want of a column in a spreadsheet.
- OFFICERS AND OWNERS HAVE THEIR OWN RULES. Depending on the state and the entity, owner payroll may be excluded, included at a statutory minimum, or capped at a maximum. Getting this wrong in either direction is common and expensive, and it is settled by election paperwork rather than by argument at audit.
- IGNORING THE AUDIT IS THE WORST AVAILABLE OPTION. A carrier that cannot complete an audit will generally estimate one, and an estimated audit is punitive by design — commonly a large multiple of the expiring premium. It also becomes a cancellation and a black mark that follows you to the next carrier, who will ask why.
- THE AUDIT CAN GO THE OTHER WAY. If you shrank, or you moved staff into lower-rated work, the audit produces a return premium. Nobody chases these as hard as the carrier chases a bill, which is a reason to do the audit properly in a bad year rather than a good one.
Related questions
- What will the auditor actually ask for?
- Payroll records for the policy period, broken down by employee and by the work each of them did; your quarterly state and federal payroll tax filings, which the auditor uses to verify the payroll figure; a list of subcontractors with what you paid each of them and a certificate of insurance for each; and usually your general ledger or profit and loss. Nothing on that list is unusual, and everything on it is easier to assemble before the appointment than during it.
- A subcontractor was insured, but I never got the certificate. Does that count?
- Generally not, and this is the single most expensive gap in the whole exercise. Most auditors work from documentation rather than from what was true, so a sub who genuinely held coverage but never sent proof gets treated as uninsured and their pay is added to your payroll. It is frequently possible to obtain the certificate retroactively from the sub or their agent, so if you are facing a bill built this way, that is the first thing to chase before disputing anything.
- What a certificate does and does not prove
- Can I dispute an audit I think is wrong?
- Yes, and disputes succeed regularly — on records rather than on argument. There is usually a limited window to object after the audit statement is issued, so raise it immediately rather than when the invoice becomes uncomfortable. What wins is documentation: payroll separated by class, overtime broken out, certificates for subs, and evidence for how staff actually spend their time. What loses is a phone call saying the number feels too high.
- How do I make sure this never happens again?
- Revise the estimate every renewal, deliberately, using real figures rather than last year’s number. Keep payroll records that separate class of work and break out overtime. Collect a certificate from every subcontractor before they start and diary the expiry. And if your premium has been flat for several years while the business has grown, treat that as a warning rather than as good news — it means the audit is accumulating somewhere.
- How premium audits work across every policy
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Written by the licensed brokers at Boring Insurance. Last updated 2026-08-22. See all guides.