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California workers' comp rates explained

By Richard Vaughn CPCU, ARM, AIS. Reviewed November 8, 2026. Richard is an insurance professional, not an attorney. This page explains the law; it is not legal advice.

No one sets the rate

California does not set workers' compensation rates. There is no manual rate that every insurer charges and no maximum the state enforces; each insurer files its own rates with the Department of Insurance before using them (Insurance Code §11735). Instead, a licensed rating organization gathers statistics and develops advisory pure premium rates, the Insurance Commissioner approves them, and each insurer decides what to charge on top. The system has four layers, and a quote is the product of all four.

Layer one: the classification

Every kind of work is assigned a four-digit classification code under the Standard Classification System developed by the Workers' Compensation Insurance Rating Bureau of California (WCIRB), the rating organization the Insurance Commissioner has designated to gather statistics and develop the classification system and manual rules all insurers must follow (Insurance Code §11734(b), (c)). A classification groups businesses with similar operations and similar loss experience. Clerical office employees, outside salespersons and a handful of other "standard exceptions" are classified separately from the governing class when the records support it; otherwise all payroll takes the classification of the business. The WCIRB inspects risks to verify classifications (Insurance Code §11750.3(d)), and a misclassified business is corrected at audit or inspection, with the premium adjusted accordingly.

Layer two: the advisory pure premium rate

For each classification the WCIRB develops a pure premium rate per $100 of payroll: the amount needed to pay expected losses and loss adjustment expense for that class, with nothing for insurer overhead or profit. It submits the rates to the Insurance Commissioner (Insurance Code §11750.3(b)), who holds a public hearing and adopts advisory rates. For policies incepting on or after September 1, 2026, the Commissioner adopted an average advisory pure premium rate of $1.65 per $100 of payroll, a 6.6% increase over the 2025 approved average and less than the 10.4% increase the WCIRB had proposed. The Department's actuaries cited rising medical treatment and medical-legal costs, a projected increase in cumulative trauma claims and higher claim-adjusting expense, partly offset by wage growth.

The rates are advisory. No insurer is required to use them, and the average conceals a range across classes that runs from well under a dollar per $100 for clerical work to many times that for roofing and framing.

Layer three: the insurer's filed rate

Each insurer files its rates and supplementary rate information with the Department of Insurance at least 30 days before using them, and the filings are public (Insurance Code §11735(a), (b)). The Insurance Code requires that rates be adequate to cover the insurer's losses and expenses and not tend to create a monopoly, with a presumption against any non-State Fund insurer holding 20% or more of the market (Insurance Code §11732). Beyond that, the insurer sets its own rates. An insurer may also, on joint written application with the insured, use a rate above its filed rate for a specific risk (Insurance Code §11735(c)).

Layer four: your modification and adjustments

The premium from the filed rate is then multiplied by your experience modification, if you qualify for one, and adjusted by any schedule credit or debit, premium discount for size, deductible credit and the policy's minimum premium and expense constant.

The experience modification is computed by the WCIRB under the uniform experience rating plan every insurer must apply (Insurance Code §11734(a)). It compares your actual losses over the rating period to the losses expected for an employer of your size in your classifications; a ratio below one is a credit, above one a surcharge. The plan splits each loss into a primary portion that counts in full and an excess portion that does not, excludes the first $250 of every claim, and caps the effect of any single claim at 25 points, so three small claims typically raise a modification more than one large one. Experience rating is mandatory for every employer that meets the eligibility threshold. The modification follows the business across insurers.

Schedule rating is the insurer's discretionary adjustment, within a filed maximum, for characteristics of the account the class rate does not capture. It is where an agent's advocacy and a documented safety program show up in the number.

Reading a quote

A workers' compensation quote lists each classification with its payroll, the insurer's rate per $100 and the resulting premium; then the experience modification; then schedule rating and other adjustments; then the expense constant and any terrorism or assessment charges; and finally the estimated annual premium. The two figures to compare across quotes are the rate per $100 for your governing class, which shows the insurer's filed rate, and the net schedule rating, which shows its view of your account. The estimated premium is only as good as the payroll estimate behind it, which is what the premium audit corrects after the fact. The cost page puts the pieces into an estimator.

Questions people ask

Richard Vaughn CPCU, ARM, AIS

Richard Vaughn spent 35 years in commercial property and casualty insurance, most of it in workers' compensation: running a self-insured group, auditing premiums, and implementing claims systems for carriers and third-party administrators. He is not an attorney. dickvaughn.com