What triggers a workers comp audit?

Annual policy true-up plus payroll growth, new states, class-code changes, or heavy subcontractor use. Auditors reconcile payroll to 941s and test classification.

How are premiums calculated?

Rate per $100 of payroll by class code times experience mod, plus officer minimums. Misclassification and missing sub certs inflate the bill.

Are officers and subs covered?

Officers often included or must opt out formally by state; uninsured subs get charged to you without certificates.

How do you dispute findings?

Provide job descriptions, payroll splits by duties, sub COIs, and overtime separation where allowed. Appeal in writing before binding endorsement.

TAX

Workers Comp Audit Guide 2026: Class Codes, Payroll Tie, and Premium Control

BATO Editorial Team September 05, 2026 2 min read

Prep Checklist

Payroll register = 941 = GL by class — see Payroll Year-End.
Class codes by duties, not titles; split multi-duty with time logs.
Officer elections filed; sub COIs current.
Overtime separated where state allows.
Multi-state payroll IDs current — see Multi-State.

Pair with Payroll Guide, 1099 vs W-2, Compliance Checklist, and Insurance.

Common Overcharges

Finding	Fix
Clerical in shop rate	Time-split memo + descriptions
Uninsured sub charged	Collect COI or back-charge contractually
Overtime included	Separate where allowed with payroll proof
Officer mis-included	Election form + payroll proof

Retain packet per Record Retention and PBC.

Worked Example: $900k Payroll, Wrong Codes

Class	Payroll	Rate/100	Premium
Clerical 8810 (correct for 6 office staff, $420k)	$420,000	$0.35	$1,470
Plumbing 5183 (correct for 8 field staff, $480k)	$480,000	$4.20	$20,160
Correct total	$900,000		$21,630
If all $900k mis-coded to 5183	$900,000	$4.20	$37,800

One code error costs $16,170 — 75% overcharge — before experience mod. The auditor won’t find this for you; the broker might, but only if you send payroll split by duties before the audit. Multi-duty employees (estimator who also runs jobsites) need time-split logs; without them, the higher-rated code applies to all hours.

Subcontractor Certificates: The Other Leak

Uninsured subs get charged to your policy at the sub’s trade rate. A $200k uninsured framing sub at ~$9/100 adds $18,000 to your bill. Controls that work:

No first payment without COI. Collect workers-comp (and GL) certificates before work starts, not at audit. Calendar expiry — a COI that lapsed mid-job leaves that period’s payments chargeable.
Contractual back-charge. Prime contracts should let you back-charge premium for uninsured subs; without the clause, you absorb it.
1099 cross-check. Every 1099 over $600 for trade labor without a matching COI is audit exposure — reconcile the vendor file quarterly — see 1099 vs W-2.

Officer Inclusion Rules (State Traps)

Situation	Typical treatment
Corp officers in most states	Included up to payroll cap; formal opt-out with ownership threshold
LLC members	Excluded in many states, included in others — confirm per state
Sole proprietors/partners	Excluded unless electing coverage
Multi-state officers	Rules follow work state — see Multi-State

File elections before the policy year starts; mid-year changes invite disputes. Include officer payroll correctly in the Payroll Year-End tie-out so comp and comp-audit agree.