California Workers' Compensation Premium Audit: Records to Prepare

An audit is not the same as a renewal review

A premium audit compares the payroll and operations you actually ran during the policy period against the estimates the policy was built on; a renewal review looks ahead at the next term. The audit looks backward. If your actual payroll was higher than estimated, additional premium may be owed; if it was lower, the terms of your policy determine whether any adjustment is available and in what amount. Do not assume an audit produces a refund — the outcome depends on your policy's premium provisions, the classifications, and the actual records. The California Department of Insurance notes that workers' compensation premium is typically based on payroll and classification, and that reporting changes during the term can keep estimates closer to actual exposure. Treat the audit as a reconciliation, not a new quote.

Confirm who is auditing and the policy period

Before you share anything, confirm the auditor's identity and which policy period the audit covers. A premium audit is normally conducted by your carrier or a firm working on its behalf for a specific term; confirm the contact and the policy period in writing before responding. Do not send sensitive records to an unverified address. Ask your insurer's authorized representative how the audit will be conducted, what records are requested, and through what secure channel — and use that channel rather than email for payroll registers, tax documents, or anything containing employee identifiers.

A practical records pack to prepare

Gather the records the audit is likely to reconcile against. You do not need to send everything at once — confirm what your auditor actually requests — but having these organized makes the audit faster and more accurate. Where a record is missing, identify the gap and ask which existing source documents can support reconciliation; do not invent amounts or unsupported allocations.

• Payroll register for the audit period, reconciled to your books
• Reconciling payroll records to tax filings (for example, quarterly wage reports) where the auditor requests them
• General ledger or income statement detail the auditor asks for
• Job duties and operational changes during the period — new services, locations, or methods of work that affect classification
• Subcontractor payments, the contracts that allocate the work, and a plain description of what each subcontractor actually did
• Evidence of coverage for subcontractors (certificates) and any applicable endorsements — a waiver or exemption form by itself does not establish worker status or premium treatment
• Current policy declarations and endorsements the auditor references
• Prior audit correspondence or adjustments, where requested

Actual duties, not job titles

Workers' compensation is typically rated on payroll by classification, and classification turns on the actual work performed — not the job title on a pay stub. Be ready to describe what each role actually did during the period, and ask the auditor how duties that span more than one class are treated. Do not self-assign the cheapest class code to reduce premium; misclassification can create retroactive exposure and is scrutinized. If you disagree with a proposed classification, ask the auditor or your insurer's authorized representative to explain the basis in writing.

A COI or 1099 does not decide worker status

A subcontractor's certificate of insurance and a 1099 form are useful records, but neither by itself determines whether a worker is an employee for workers' compensation purposes or how their pay is treated in the audit. Worker status and premium treatment depend on the actual facts and California rules. Gather the certificates and contracts, and be ready to explain the working relationship — but do not rely on a 1099 label alone to conclude someone is excluded from your payroll. Ask your insurer's authorized representative how subcontractor payments are treated and what documentation supports the treatment. For broader workers' compensation questions on employees, subcontractors, and premium basis, see our companion guide.

Workers' compensation questions California employers should ask →

An audit-result review worksheet

When the audit result arrives, review it against your records so you can see what changed and ask about anything that does not match. This is a review worksheet, not a dispute template — and ignoring a bill or a disputed item does not make it go away.

• Audit period — does it match the policy period you expected?
• Payroll by class — does each class total match your reconciled records?
• Classification basis — which class code applies to each role, and does the duty description fit the actual work?
• Subcontractor treatment — were subcontractor payments included or excluded, and on what basis?
• Endorsements and exclusions — were owner, officer, or other exclusions applied as endorsed?
• Itemized questions — for any line that does not match your records, ask the auditor or your insurer's authorized representative for the basis in writing
• Do not ignore a bill or a disputed deadline — confirm the due date and any dispute process with your insurer, and send unresolved items to your broker or counsel

Audit outcome vs. future payroll estimate

An audit reconciles the past period; it does not set your next-term estimate by itself. If the audit changes your payroll or classification picture, use it to update the estimate for the next policy period so the new term starts closer to actual exposure. For a forward-looking review of your whole program at renewal, see our renewal checklist rather than treating the audit as a renewal.

Business insurance renewal checklist for California companies →

An illustrative example

Suppose a seasonal Central Coast business added a second crew mid-year for a busy stretch but kept its workers' compensation payroll estimate at the original, smaller headcount. At audit, the reconciled payroll register shows more wages in a new role than the estimate reflected, and the job duties do not match the class originally assigned. The audit prompts questions about the correct classification for the new duties and the additional premium for the added payroll. This is a hypothetical illustration, not an actual case — the point is not that the audit produces a refund or a penalty. It reconciles actual records against the estimate, and the outcome depends on the policy's premium terms, the classification, and the documented duties. No specific premium figure is implied, and no claim or adjustment is promised.

Sources reviewed

• California Department of Insurance — Workers' Compensation Insurance Guide
• State Farm — Premium Audit