How a Michigan Contractor Cut a Surprise Workers Comp Audit Bill in Half

How a Michigan Contractor Cut a Surprise Workers Comp Audit Bill in Half

This is an illustrative composite based on patterns that recur across trades businesses. It does not describe a specific client, the figures are illustrative rather than actual, and nothing here should be read as a promise of a similar result.

The envelope arrives in the spring and it does not look important. Then the owner opens it and the workers comp audit bill is roughly triple what the estimated premium was, due in thirty days.

The first assumption is almost always that the number is simply owed. That assumption is usually wrong, and it is expensive, because the dispute window is short and it starts running the day the invoice is issued.

Here is how a Detroit-area specialty contractor with about twenty-five people worked through one.

What a Workers Comp Premium Audit Actually Does

A workers compensation policy is priced at the start of the year on estimated payroll. At the end of the year, the carrier trues that estimate up against what actually happened.

The calculation has three inputs and nothing else: how much payroll there was, which class code each dollar of it belongs to, and whether any subcontractors have to be treated as your payroll because they could not prove their own coverage.

That is the whole thing. Which means a shocking audit bill is not a mystery. It is one of three inputs being wrong, and all three are records problems rather than insurance problems.

Finding One: Everyone Was Priced as a Field Employee

The contractor's payroll export produced a single total. Gross wages, one number, one company.

Workers comp rates are set per hundred dollars of payroll by class code, and the spread between a clerical office code and a field trades code is large. When payroll arrives as one undifferentiated total, the auditor has little choice but to apply the governing field classification to all of it.

So the office manager, the estimator, and the part-time bookkeeper were all being priced as though they spent their days on a job site.

Splitting payroll by class code is a payroll-system configuration task, not an argument. The relevant point for the audit is that the split has to be supported by records, meaning job descriptions and time detail that show who did what, not a spreadsheet built after the invoice arrived.

Finding Two: The Certificates Existed, in an Email Folder

Under most states' rules and most carrier contracts, a subcontractor who cannot produce evidence of workers compensation coverage gets charged back to the hiring contractor's payroll. The logic is straightforward. If the sub is uninsured, the hiring contractor's policy is the one carrying the exposure.

This contractor collected certificates of insurance. They were in an inbox, some expired mid-project, and several were for general liability only with no workers compensation line at all.

The audit swept in a meaningful share of subcontractor payments as payroll on that basis. Most of it was recoverable, because valid certificates did exist for the relevant periods and simply had not been produced in a form anyone could match to the work.

The lasting fix was procedural rather than financial: a certificate tracker with expiration dates, and a rule that no subcontractor invoice gets paid without a current certificate showing workers compensation coverage on file.

Finding Three: Not All Pay Is Includable Pay

The third input was the smallest in dollars and the one nobody knew existed.

Rules vary by state and by manual, but the audit base is generally not simply gross payroll. Overtime is a common example. In many jurisdictions the premium portion of overtime pay, meaning the extra half in time and a half, is excluded from the audit base when payroll records show it separately. Certain reimbursements, severance, and some benefit payments are also treated differently from ordinary wages.

The critical condition is the same one from finding one: the exclusion generally depends on the records showing the amounts separately. A payroll report that lists one gross figure per employee does not support any of it.

The Approach

The sequence mattered more than any single argument.

First, rebuild payroll by employee and by class code for the audit period, with job duties documented. Second, collect every certificate of insurance, match each to the specific project and dates, and identify which subcontractor charges were properly excludable and which were genuinely not. Third, separate the payroll components that the manual treats differently, using the actual payroll register rather than a summary.

Only then file the dispute, inside the carrier's stated window, as a documentation package rather than a letter of complaint. Auditors respond to records. They do not respond to the position that the number feels too high.

Illustratively, that package cut the revised invoice roughly in half. A material share of the original assessment was correct and stayed, which is the normal outcome. The remaining exposure went from a surprise to a known number with a payment plan attached.

The more valuable result was structural. Payroll now reports by class code automatically, certificates are tracked with expiration dates, and next year's audit becomes a two-hour records handoff instead of a crisis.

The Balanced View on a Workers Comp Audit Bill

A few things deserve to be said plainly.

Premium audits are contractual, and carriers are entitled to true up the estimate. Being audited is not an accusation.

Disputes have deadlines, and they are shorter than most owners expect. A package assembled after the window closes is worth very little.

Some findings are correct. In this composite, a real portion of the assessment survived review because the underlying facts supported it.

And a reduction in one year does not predict another. Payroll mix changes, class codes get reassigned, experience modification factors move, and a clean audit this year is the result of this year's records rather than a permanent condition.

Where the Accounting Work Sits

Almost none of the above is an insurance task. It is payroll configuration, document control, and records discipline, which is why it usually lands with whoever keeps the books.

Grace CPA Services is a Sam's List accounting firm founded in 2008 and based in Grosse Pointe Woods, Michigan, working with small business owners, real estate investors, venture-backed startups, and solopreneurs. Setting up payroll to report by class code, maintaining a certificate tracker, and keeping payroll components separated in the register is unglamorous recurring work, and it is what turns an annual audit from a threat into a formality.

Grace CPA has 9 verified client reviews on Sam's List as of 2026-08-06. Reviews reflect the experiences of individual clients, do not represent an endorsement by Sam's List, and are not indicative of future results.

To be clear about limits: clean records improve your position in an audit, they do not determine the outcome, and no accountant can promise a reduction. Insurance classification questions ultimately belong with your carrier, your agent, and where the amounts are large, counsel. Confirm scope and fit before engaging, and compare firms in the Sam's List accountant directory.

Frequently Asked Questions

Why is my workers comp audit bill so much higher than my premium? Almost always one of three things: payroll came in higher than estimated, employees were classified into a higher-rated class code than their actual duties warrant, or subcontractors without proof of their own coverage were added to your payroll base. The first is legitimate. The second and third are records problems and are often correctable.

Can I dispute a workers compensation premium audit? Generally yes, and carriers have a stated process and a deadline for it. What succeeds is documentation: payroll detail by employee and class code, job descriptions supporting the classifications, and certificates of insurance matched to specific subcontractors and project dates. What does not succeed is an argument that the total seems unreasonable.

Do I have to pay workers comp on subcontractors? If a subcontractor cannot produce evidence of their own workers compensation coverage for the period they worked for you, their payments are commonly charged back to your policy as payroll. Rules vary by state and by carrier contract, including how owner-operators and sole proprietors are treated, so confirm the specific requirement in the states where you operate.

How do I prepare for next year's premium audit? Configure payroll to report by class code rather than as one total, keep job descriptions current so classifications are supportable, collect a certificate of insurance showing workers compensation coverage before the first subcontractor invoice is paid and track expiration dates, and keep overtime premium and reimbursements separated in the payroll register. Most of a clean audit is decided long before the auditor calls.

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About the author: Kimberly Green is the cofounder of Sam's List, where business owners and high earners find vetted CPAs, financial advisors, and fractional CFOs. She's met one-on-one with 400+ financial professionals and writes from the real data behind thousands of client-advisor matches. Ask her anything about finding an accountant - she's heard it all, including the questions people are afraid to ask.