Why Your Workers’ Comp Audit Came With a Huge Bill — and Subcontractors Are Usually Why

You finished the year, your workers’ comp policy expired, and a few weeks later the audit landed — with a bill for thousands you didn’t budget for. If you hire subcontractors, there’s a good chance they’re the reason.

How an uninsured sub becomes your payroll

Workers’ comp premium is based on payroll. At audit, your carrier reviews what you actually paid out. Here’s the part that catches contractors off guard: if a subcontractor can’t prove they carried their own workers’ comp coverage, the auditor can treat everything you paid that sub — including materials — as your payroll, and charge premium on it at your governing (often highest) class rate.

State law backs this up. Most states make the upstream contractor responsible for an uninsured sub’s injured workers, so the carrier prices that exposure. As one state insurance regulator puts it: without evidence the sub had coverage, “your insurance company will charge for the subcontractor according to the services that subcontractor provided.”

Why “I had a certificate” often isn’t enough

A certificate of insurance (COI) on file does not automatically exclude a sub. To actually keep them off your audit, the COI has to clear three tests:

• It shows a workers’ comp line — general liability alone doesn’t count.
• Limits are adequate for your policy/state minimums.
• The dates cover the whole period the sub worked for you. If coverage started after they began, or lapsed before they finished, the gap is chargeable to you.

Miss any one and the auditor can add that sub’s pay back in. Use the free COI Gap Checker to see which of your subs would pass.

What the bill can look like

The math is simple and brutal. Say you paid $120,000 to subs who couldn’t document coverage, and you’re a roofer. At a class rate around $18 per $100 of payroll, that’s roughly $21,600 in extra premium — for work you already paid for once. Reported premium increases from missing sub COIs commonly land in the 25–200% range, and your carrier can re-bill up to three years back.

Estimate your own exposure with the free calculator →

How to stop it before next audit

• Collect a COI before the first payment — not at audit time.
• Verify the WC line and the dates against when the sub actually worked.
• Re-collect when a COI expires mid-project. A renewal you never asked for is a gap you’ll pay for.
• Keep the certificates organized by project and date so you can hand the auditor proof, not a shoebox.

This is exactly the busywork that creates surprise bills — and exactly what we’re automating. The tool watches every sub payment against their coverage window all year and flags gaps while you can still fix them.