You hired a subcontractor in March. He told you he had insurance. He probably did. Ten months later your auditor asks for the certificate, you cannot find one, and the carrier charges you premium on his payroll as though he had been your employee.
On residential carpentry in a state where the workers' comp rate runs around $19.51 per $100 of payroll, a $60,000 subcontract turns into roughly $11,700 of additional premium on a bill you did not budget for. That is the single most common audit surprise in contracting, and it is entirely preventable with a filing cabinet.
Why the Charge Is Legitimate
This is not a carrier being difficult. Most states make the hiring contractor the statutory employer of an uninsured subcontractor's workers, and the audit rule follows the statute.
- Florida — under Statute 440.10, a contractor who sublets work becomes the statutory employer of an uninsured subcontractor's workers, and the statute requires obtaining evidence of coverage, or a valid exemption certificate, before the work is performed.
- North Carolina — under N.C. Gen. Stat. ยง97-19, a principal contractor can be held liable for benefits to a subcontractor's injured worker if it failed to obtain proper proof of coverage.
- Michigan — workers' compensation liability transfers from an uninsured subcontractor to the general contractor, though the contractor retains the right to sue the sub for reimbursement. A properly executed exclusion form on file with the agency serves as the alternative to a certificate.
The details differ but the shape is identical everywhere: the state does not want an injured construction worker with nobody to pay the claim, so it assigns the risk upward to whoever had the money to hire. Your carrier prices that assigned risk at audit.
The Certificate Has to Cover the Dates, Not the Meeting
The most frequent failure is not a missing certificate. It is a certificate that does not line up with when the work happened.
Auditors examine certificates far more aggressively than they used to. Subs get picked up as uninsured even when a certificate is on file, because:
- The policy expired mid-project. You collected a valid certificate in January; the policy lapsed in April; the work ran through August. The uncovered months get charged.
- The policy was cancelled mid-term. Auditors now dig into this specifically, asking you to break down when and how much you paid the sub during the period so they can add the uncovered portion.
- The certificate shows only one coverage. A certificate evidencing workers' comp but not general liability means you get charged for GL. Workers' comp and employers' liability are not general liability, and the two are audited separately.
- The sub's limits are below yours. Carriers commonly expect the sub's liability limits to be equal to or greater than yours — typically $1M per occurrence and $2M aggregate. A sub carrying less can be treated as underinsured for your purposes.
- You are not named as additional insured. Many carriers want to see this on the certificate before treating the sub as properly insured for your file.
A certificate is a snapshot of the day it was printed, not a guarantee of the policy term — our guide to what a certificate of insurance actually proves covers what the ACORD form does and does not do.
A Verification Routine That Survives an Audit
- Never take the sub's word for it. The certificate has to be in your hands before work begins — not promised, not emailed later, not "my agent will send it."
- Require both coverages. Workers' compensation with employers' liability, and general liability, on the same certificate or on two.
- Check the dates against your job dates. If the policy expires before the project ends, diary the expiry and collect a renewal certificate before it lapses.
- Check the limits against yours. Equal or greater. Note the general aggregate is shared across the sub's whole year and every job they run, so it may already be partly eroded.
- Get named as certificate holder, and as additional insured where the contract requires it. These are different things — see additional insured vs certificate holder.
- For exempt solo subs, collect the exemption certificate instead — and check it has not expired. Some states, like Montana, make verifying an independent contractor's exemption certificate a condition of avoiding liability for their injuries.
- Document the scope and dates of work. Auditors increasingly ask what the sub did and when. Good records limit exposure when a policy turns out to have been cancelled mid-term.
Withholding: The Practice Nobody Enjoys but Everyone Should Use
It is standard in the industry to deduct from payments to uninsured subs to offset the audit charge you will absorb. The mechanic is straightforward: withhold the amount you expect to be charged, tell the sub you will reimburse it once the certificate is in hand, and follow through when it arrives.
Contractors lose thousands of dollars a year by being too polite to do this. The deduction rate is not arbitrary — it is the workers' comp rate per $100 of payroll for that class, which is why the carpentry example above works out to roughly 19.5%. Some builders deduct only on workers' comp because the charges are much higher there than on general liability, but skipping the GL deduction leaves money on the table and removes the sub's incentive to go get covered.
A cleaner version of the same idea: make the certificate a condition of the first payment rather than a condition of the last one.
The Other Half of the Problem: Classification
Collecting certificates fixes the uninsured-sub charge. It does not fix the second-largest audit surprise, which is subcontractor payments being assigned to the wrong classification, or work you consider subcontracted being recharacterised as employment.
If a "subcontractor" works only for you, uses your tools, and follows your schedule, an auditor or a state agency may treat them as an employee regardless of what the agreement says and regardless of the certificate on file. That reclassification is more expensive than the uninsured-sub charge because it carries back-premium and potential penalties. Our workers' comp premium audit guide covers how the rest of the audit works, and the EMR calculator shows how claims from that arrangement would flow into your experience modification.
Bottom Line
Get a current certificate from every subcontractor before work starts, covering the dates the work actually happens, showing both workers' comp and general liability at limits equal to or greater than yours. Diary every expiry. Withhold from payment until the certificate arrives. The alternative is paying premium on someone else's payroll at a rate that can approach 20% of what you paid them — a bill that arrives a year late for a problem that took five minutes to prevent.
Frequently Asked Questions
Why am I charged for uninsured subcontractors at audit?
Most states make the hiring contractor the statutory employer of an uninsured subcontractor's workers. Florida Statute 440.10 requires obtaining evidence of coverage or a valid exemption certificate before work is performed; North Carolina's N.C. Gen. Stat. section 97-19 makes a principal contractor liable for benefits if it failed to obtain proof; Michigan transfers the liability to the general contractor. Your carrier prices that assigned risk by charging premium on the sub's payroll as if they were your employee.
How much does an uninsured subcontractor cost me at audit?
The charge is based on the workers' comp rate per $100 of payroll for the applicable classification, so it scales with how hazardous the work is. Using a published example where residential carpentry runs about $19.51 per $100, a $60,000 subcontract would generate roughly $11,700 of additional premium. That rate is also the percentage you would need to withhold from payment to offset the exposure.
What should a subcontractor's certificate of insurance show?
Workers' compensation with employers' liability and general liability, at limits equal to or greater than your own - commonly $1 million per occurrence and $2 million aggregate. It must cover the dates the work is actually performed, not just the date it was issued. Many carriers also want you named as additional insured on the sub's policy before treating the sub as properly insured in your file.
I have a certificate on file - can I still be charged?
Yes, and it happens often. Auditors examine certificates aggressively and pick up subs as uninsured when the policy expired mid-project, was cancelled mid-term, or evidenced only one of the two required coverages. If the policy expires before the project ends you need a renewal certificate, and auditors increasingly ask you to break down when and how much you paid the sub so they can charge any uncovered portion.
Should I withhold payment from subcontractors without certificates?
It is standard industry practice. Withhold the amount you expect to be charged at audit, tell the sub you will reimburse it once the certificate is in hand, and follow through. Contractors lose thousands of dollars a year by being too polite to do this. A cleaner version of the same idea is making the certificate a condition of the first payment rather than the last.
What if my subcontractor is exempt from workers' comp?
Collect their state exemption certificate instead of a policy certificate, and check that it has not expired. Some states make this verification a condition of avoiding liability - Montana, for example, requires confirming an independent contractor holds a valid exemption certificate or their own coverage before you hire them, or you may be held financially responsible for their injuries.
This content is for informational purposes only and does not constitute insurance, financial, or legal advice. Workers' compensation statutes, exemption rules, licensing requirements, and penalty amounts vary by state and are amended frequently — verify current rules with your state agency or licensing board before acting. Premium figures are illustrative industry ranges rather than quotes. Consult a licensed broker or attorney about your specific situation.