What Is a Workers' Comp Audit?
A workers' compensation audit is a review of your business's payroll records and employee classifications conducted by your insurance company at the end of each policy period. The purpose is to verify that the premium you paid throughout the year was based on accurate data.
When you purchase a workers' comp policy, the initial premium is calculated using estimated payroll for the upcoming year. Since actual payroll may differ from the estimate (due to hiring, layoffs, wage changes, or business growth), the audit reconciles the difference. If your actual payroll was higher than estimated, you owe additional premium. If lower, you receive a credit or refund.
The audit also verifies that employees are classified under the correct class codes. If the auditor finds employees performing work that does not match their assigned classification, the payroll may be reclassified to the appropriate code, which could increase or decrease the premium.
Types of Workers' Comp Audits
- Physical audit (in-person): An auditor visits your business to review records in person. This is the most thorough type and is common for larger businesses or complex operations.
- Voluntary / mail audit (self-audit): The insurer sends you a form to complete and return with supporting documentation. Common for small businesses with straightforward operations.
- Phone audit: The auditor contacts you by phone to review payroll figures and classifications. A middle ground between physical and mail audits.
- Interim audit: Conducted mid-policy for large or high-premium accounts to adjust the premium during the policy period rather than waiting until year-end.
The Workers' Comp Audit Process
Notification
Your insurer notifies you that an audit is due. For physical audits, you will be contacted to schedule an appointment. For mail audits, you receive a form with a deadline for return. The notification typically arrives within 30-60 days after your policy period ends.
Document Collection
Gather the required records: federal and state payroll tax returns (Form 941, state SUI reports), certificates of insurance from subcontractors, a list of all employees with job duties, overtime records, 1099 forms for independent contractors, exemption certificates for exempt officers, and the general ledger or cash disbursements journal.
Auditor Review
The auditor reviews your records and categorizes payroll by class code. They verify total payroll against your tax returns, check subcontractor certificates of insurance, identify any payroll exclusions (overtime premium, severance pay, certain benefits), and determine if any payments to subcontractors or independent contractors should be classified as payroll.
Preliminary Results
The auditor provides preliminary findings and may discuss any discrepancies with you. This is your opportunity to provide additional documentation or clarify job duties before the audit is finalized.
Final Audit Report
The insurer issues a final audit report showing the adjusted premium based on actual payroll and classifications. If the adjusted premium is higher than what you paid, you will receive an additional premium bill. If lower, you receive a credit or refund.
Common Workers' Comp Audit Mistakes
Many employers make avoidable mistakes that lead to higher audit premiums. Being aware of these pitfalls helps you prepare properly and avoid unpleasant surprises.
1. Missing Subcontractor Certificates of Insurance
This is the single most common and costly audit mistake. If you pay a subcontractor who does not have their own workers' comp insurance, the auditor will add the subcontractor's payments to your payroll at the appropriate class code rate. A $50,000 payment to an uninsured subcontractor classified as construction could add $3,900 or more to your premium.
Prevention: Require certificates of insurance from every subcontractor before they begin work. Verify the certificates are current and the policy has not been cancelled. Many insurers offer online certificate verification tools.
2. Incorrect Employee Classifications
Employees performing duties that do not match their assigned class code will be reclassified during the audit. For example, if a clerical employee (code 8810) also performs warehouse duties, the auditor may reclassify their payroll to a higher-risk warehouse code.
Prevention: Maintain accurate, up-to-date job descriptions for every employee. If an employee splits time between two types of work, discuss with your insurer whether the payroll can be split between codes.
3. Including Exempt Payroll Items
Certain types of compensation can be excluded from auditable payroll in most states:
- Overtime premium: Only the time-and-a-half premium is excluded (not the base pay). For example, if an employee earns $20/hour and works overtime at $30/hour, only the $10 premium is excluded.
- Severance pay after the employment relationship ends
- Tips (in most states, unless the employer has records of tip amounts)
- Employer-paid group insurance premiums (health, life, dental)
- Uniform allowances
Prevention: Track these items separately in your payroll records so the auditor can easily identify and exclude them.
4. Misclassifying Employees as Independent Contractors
If the auditor determines that workers you paid as independent contractors (1099 workers) should be classified as employees based on the actual working relationship, their payments will be added to your auditable payroll. The IRS and state agencies use various tests (common law test, ABC test, economic reality test) to determine worker classification.
Prevention: Ensure that individuals you classify as independent contractors truly operate independently: they control how and when they work, use their own tools, work for multiple clients, and have a genuine business operation.
5. Underestimating Payroll at Policy Inception
While an underestimate does not change your total audit premium, it creates a larger year-end audit bill (the difference between estimated and actual). This can cause cash flow problems, especially for growing businesses.
Prevention: Provide the most accurate payroll estimate possible when purchasing or renewing your policy. Account for planned hiring, raises, and overtime. Some insurers offer pay-as-you-go programs that adjust your premium monthly based on actual payroll, eliminating large audit adjustments.
How to Prepare for Your Workers' Comp Audit
Year-Round Best Practices
- Maintain organized, accurate payroll records throughout the year
- Collect certificates of insurance from subcontractors before they start work
- Track overtime separately from regular pay
- Keep 1099 records organized with signed independent contractor agreements
- Update employee job descriptions whenever duties change
- File exemption certificates for exempt officers and renew them on time
- Reconcile payroll records quarterly against tax filings
Pre-Audit Checklist
| Document | Purpose | Where to Find It |
|---|---|---|
| Form 941 (Quarterly) | Verify total payroll | Payroll service / IRS filings |
| State SUI Reports | Cross-reference payroll by state | State unemployment agency |
| Payroll Journal / Registers | Detail by employee and pay period | Payroll software / service |
| Employee List with Job Titles | Verify classifications | HR records |
| Subcontractor COIs | Prove sub's own WC coverage | Certificates on file |
| 1099 Summary (1096) | Identify independent contractor payments | Tax records |
| Overtime Records | Calculate overtime premium exclusion | Payroll records |
| Officer Exemption Certs | Exclude exempt officers | State WC agency / your files |
| General Ledger / Cash Disbursements | Identify all labor-related payments | Accounting records |
Consider a Pre-Audit Review
Many workers' comp consultants and brokers offer pre-audit review services. They review your records before the insurer's auditor arrives and identify potential issues such as misclassifications, missing subcontractor certificates, or payroll items that should be excluded. This proactive approach often saves employers money by catching and correcting errors before the official audit.
Related Calculators and Resources
Use our other free tools and guides to better understand your workers' compensation benefits:
Frequently Asked Questions
Answers to the most common questions about this topic.
A workers' comp audit (also called a premium audit) is a review conducted by your insurance company at the end of your policy period to verify that the premium you paid was based on accurate payroll and classification data. Since your initial premium is based on estimated payroll, the audit reconciles estimated versus actual payroll to determine if you owe additional premium or are entitled to a refund.
Workers' comp audits typically occur annually, at the end of each policy period. Most policies run for one year, so you can expect an audit once a year. Some insurers conduct interim audits mid-policy for large or complex accounts. Additionally, a final audit occurs when you cancel or non-renew a policy. The audit may be conducted by mail (self-audit), phone, or through an in-person visit by an auditor.
You should prepare the following for a workers' comp audit: payroll records (quarterly tax returns - Form 941, state unemployment tax reports), a list of all employees with job descriptions and class codes, certificates of insurance from subcontractors, overtime records, records of payments to independent contractors (1099s), cash disbursement journals, general ledger, certificates of exemption for exempt officers, and records of any employee benefits or perquisites.
Yes, you can dispute the results of a workers' comp audit if you believe it contains errors. Start by requesting a detailed explanation of the auditor's findings. If you disagree, file a written dispute with your insurance company within the timeframe specified in your policy (usually 30-60 days). Provide supporting documentation for your position. If you cannot resolve the dispute with the insurer, you can escalate to your state's insurance department or seek binding arbitration. Common audit disputes involve classification errors, inclusion of excluded payroll, and subcontractor coverage issues.
Refusing or failing to cooperate with a workers' comp audit can have serious consequences. Your insurer may: charge you the maximum estimated premium for the policy period, apply penalty rates or surcharges, non-renew your policy, report you to the state workers' comp authority, or pursue legal action to collect the estimated premium. Most policies include a cooperation clause requiring the insured to submit to audits. It is always better to cooperate with the audit and dispute any findings you disagree with.
To prepare effectively: (1) Maintain accurate, organized payroll records throughout the year, not just at audit time; (2) Ensure employee job descriptions match their assigned class codes; (3) Collect certificates of insurance from all subcontractors before they begin work; (4) Track overtime separately from regular pay; (5) Document payments to independent contractors with signed agreements and 1099s; (6) Keep records of exempt officers' exemption certificates; (7) Reconcile your payroll records quarterly to catch discrepancies early; (8) Consider hiring a workers' comp consultant to review your records before the audit.