Premium Audit Prep for Wisconsin Contractors: How to Avoid a Surprise Bill

Every spring, a lot of Wisconsin contractors open an envelope they were not expecting to worry about: a premium audit bill. The policy was paid in full, the year went well, and now the carrier says you owe several thousand dollars more. Premium audit prep is the single best way Wisconsin contractors can avoid that surprise, and most of the work happens long before the auditor ever calls.

This post is part of our series on the insurance terms every contractor should know. Here we walk through how a premium audit works, what the auditor will ask for, the mistakes that drive up final premiums, and a simple checklist you can use all year so the audit becomes a formality instead of a fight.

What a Premium Audit Is and Why Contractors Get One

Workers compensation and general liability policies for contractors are usually priced on estimates. At the start of the policy term, you and your agent estimate your payroll by job type, your gross sales, or the cost of work you will subcontract. The carrier charges a deposit premium based on those numbers.

After the policy period ends, the carrier checks what actually happened. That review is the premium audit. If your real payroll or sales came in higher than the estimate, you receive an additional premium bill. If they came in lower, you may receive a return premium. The audit is not an accusation of wrongdoing. It is simply how the final price of a variable policy gets settled.

Contractors see more audits than most businesses because their exposure changes so much from year to year. A big commercial job, a new crew, or a shift from residential remodeling to new construction can change the premium significantly.

Which Policies Get Audited

Workers compensation

Workers compensation is almost always auditable. Premium is calculated on payroll for each classification code, so the auditor wants to know how much you paid each type of worker. In Wisconsin, classification rules and rates are administered through the Wisconsin Compensation Rating Bureau, and a roofer, a carpenter, and an office manager can carry very different rates.

If you want the bigger picture on how this coverage works for your crew, our Wisconsin workers compensation page covers requirements and options.

General liability

Many contractor general liability policies are rated on payroll, gross receipts, or subcontracted cost, and those figures are audited the same way. Some carriers audit general liability every year, while others audit only when the premium is above a certain size or exposures shift.

Commercial auto and umbrella

Commercial auto policies are usually rated per vehicle and are less often audited, though some fleet and hired auto exposures are. Umbrella policies can also be adjusted if they are rated on the same payroll or sales base as your underlying policies.

What the Auditor Will Ask For

Audits come in three main formats. A mail or online self audit asks you to complete a form and upload records. A phone or virtual audit walks through your numbers with an auditor. A physical audit sends someone to your office to review records in person, which is more common for larger accounts. Whatever the format, expect requests like these:

• Payroll journals or payroll service reports for the full policy period, not just the calendar year.

• Quarterly federal Form 941 filings and Wisconsin unemployment wage reports, which the auditor uses to confirm total payroll.

• A breakdown of payroll by employee and by type of work performed.

• Overtime records showing straight time and overtime premium pay separately.

• A list of subcontractors paid during the period, with amounts paid and certificates of insurance for each.

• Gross sales or receipts figures, often supported by profit and loss statements or tax returns.

• Owner and officer information, including whether any owners elected to be excluded from coverage.

One timing detail trips people up. Your policy period may run from, say, April to April, while your payroll reports run on the calendar year. The auditor needs figures that match the policy dates, so it helps to keep payroll summaries you can split by month.

The Mistakes That Lead to Surprise Bills

Uninsured subcontractors

This is the most expensive audit problem for Wisconsin contractors. If you pay a subcontractor who cannot show proof of their own workers compensation and general liability for the dates they worked, many carriers will treat what you paid them as if it were your own payroll. That can add a large amount of premium at the highest rated class code on your policy.

The fix is simple but requires discipline: collect a current certificate before any sub starts work, and keep it on file. Our guide to certificates of insurance for Wisconsin contractors explains what a certificate proves, what it does not, and which dates to check.

Everyone lumped into the highest class

If your records do not show which employees did which kind of work, the auditor may place all payroll in the highest rated classification. A foreman who spends half the week estimating, or an employee who splits time between shop work and field work, can be rated more accurately only when your records support the split. Keep job codes or time records that show how hours were divided, and ask your agent how your carrier handles split classifications.

Overtime not separated

Many workers compensation rules let the extra portion of overtime pay be left out of the premium calculation, but only when your payroll records show it separately. If overtime is buried in gross wages, you may pay premium on the full amount. Rules vary by carrier and policy, so confirm with your agent how overtime is treated before audit season.

Estimates that were never updated

Growth is good news, but a policy written on last year's payroll will not keep up with a business that added two crews in June. When payroll or revenue changes meaningfully during the year, tell your agent. Updating the estimate mid term spreads the cost across your installments instead of landing it in one bill after the policy has ended.

A Year Round Premium Audit Checklist

Contractors who sail through audits tend to follow the same simple routine:

• Review your payroll and sales estimates with your agent at every renewal, using real numbers from the past year.

• Use consistent job titles and descriptions in payroll that match the work your employees actually do.

• Track hours by type of work for anyone who performs more than one job function.

• Record overtime premium pay as a separate line in your payroll system.

• Collect and file a current certificate of insurance from every subcontractor before they start, and track expiration dates.

• Keep a running subcontractor payment log with names, dates, and amounts.

• Call your agent when you land a large job, hire a new crew, or change the type of work you perform.

• Respond to audit requests promptly. An incomplete or ignored audit can lead to an estimated charge that is often higher than an accurate one.

If you work as a general contractor managing several trades, these habits matter even more. Our general contractor insurance guide covers the broader coverage picture for firms that hire subs.

What to Do If You Disagree With Your Audit

Auditors make mistakes too. A misread class code, a subcontractor whose certificate was overlooked, or payroll counted outside the policy dates can all inflate a bill. If the result looks wrong, do not simply pay it or ignore it.

• Ask for the auditor's worksheet so you can see exactly how each figure was calculated.

• Compare the classifications and payroll totals against your own records.

• Gather missing documents, such as subcontractor certificates or overtime reports, and submit them with a written request for review.

• Bring your agent in early. An independent agent can communicate with the carrier on your behalf and help request a revised audit when the records support it.

MM Insurance Associates has helped Wisconsin contractors prepare for and challenge audits since 1997. We look at how your business insurance program is rated, line up the right classifications at renewal, and help keep the final bill close to what you budgeted.

Questions about how audits affect your crew's coverage? Our workers compensation team can walk through your class codes and payroll before the next renewal.

Frequently Asked Questions

What is a premium audit for contractors?

A premium audit is the carrier's review of your actual payroll, sales, or subcontracted costs after the policy period ends. It compares those figures to the estimates used to set your deposit premium and results in an additional bill or a return premium.

Why did I owe more money after my workers comp audit?

The most common reasons are payroll that grew beyond the estimate, payments to subcontractors who could not show their own insurance, and payroll placed in a higher rated class because records did not show how work was divided.

Do I need certificates of insurance from my subcontractors for an audit?

Yes. Keep a current certificate for every subcontractor that covers the dates they worked for you. Without one, many carriers will count what you paid that sub as your own payroll for premium purposes.

How long does a premium audit take?

A mail or online audit can be finished in a day or two once your records are ready. Phone and physical audits are scheduled with the auditor and usually take a few hours, depending on the size of your business.

What happens if I ignore an audit request?

The carrier may charge an estimated premium, which is often higher than an accurate audit would produce, and some carriers may cancel or decline to renew the policy. It is always better to respond and ask for help if you need more time.

Can I dispute the results of a premium audit?

Yes. Request the auditor's worksheet, compare it to your records, and submit any missing documentation with a written request for review. Your agent can help you work through the process with the carrier.

Make Your Next Audit a Formality

A premium audit should confirm the numbers you already planned for, not upend your budget. Call MM Insurance Associates at (262) 754-4736 to review your payroll estimates, class codes, and subcontractor records before your next renewal. Our New Berlin team works with contractors across Milwaukee, Waukesha, and the rest of Wisconsin.

You can also get started online through our customer portal and we will follow up to help you prepare for your next audit.