California workers’ compensation rates currently average $1.52 per $100 of payroll, the advisory pure premium benchmark set by the Insurance Commissioner effective September 1, 2025.1WCIRB California. Insurance Commissioner Issues September 1, 2025 Pure Premium Rate Filing Decision What your business actually pays can sit far above or below that average. A clerical office might pay a fraction of a dollar per $100 of payroll. A roofing crew can pay more than $20. The three things that decide where you land are the industry code assigned to your work, your own claims history, and which insurer writes the policy.
How the Premium Is Calculated
Every California workers’ compensation premium starts with the same arithmetic. You take the rate assigned to your classification code, multiply it by your experience modification factor, then multiply by your total payroll divided by 100.
A worked example: if your classification rate is $2.50 per $100 of payroll, your experience modification is 0.90, and your annual payroll is $500,000, the base premium is $2.50 × 0.90 × 5,000, or $11,250. The insurer then adds its own expense loading and the mandatory state assessment on top of that number to produce your final bill.
Each piece of the formula behaves differently. The classification rate is largely fixed by what your business does. The experience modifier moves with your claims history. Payroll moves with hiring, wages, and overtime. And the loading an insurer stacks on top varies from carrier to carrier, which is why quotes for the same risk are rarely identical.
Classification Codes and the Range of Rates
California groups employers into roughly 700 industry classifications, each meant to capture a similar level of workplace injury risk.2WCIRB California. Standard Classification System The code assigned to your business drives the single largest chunk of your premium.
The spread between low-risk and high-risk classes is dramatic. Clerical office operations (code 8810) sit at the bottom of the scale. Roofing operations (codes 5552 and 5553) sit near the top, with approved advisory pure premium rates of $21.22 per $100 of payroll for lower-wage roofing workers and $13.60 for higher-wage workers as of September 2025.3WCIRB California. WCIRB Classification and Rating Committee Presentation A roofer with $300,000 in annual payroll faces a pure premium base above $40,000 before any insurer markup. An office with the same payroll might owe a few hundred dollars.
Getting the code right matters. The California Department of Insurance lets employers compare manual base rates across carriers using each business’s four-digit classification code.4California Department of Insurance. Workers’ Compensation Rate Comparison If your workforce is coded wrong during the policy period, the auditor will fix it after the fact and back-charge you.
Classification also interacts with how you engage workers. Under California’s ABC test, codified through AB 5, a worker is presumed to be your employee unless the business can prove all three of the following: the worker is free from your control in how the work is done, the work falls outside your usual business, and the worker has an independently established trade or business.5Franchise Tax Board. Worker Classification and AB 5 FAQs If any prong fails, the person is an employee for workers’ compensation purposes and their pay gets folded into your premium.
Your Experience Modification Factor
The experience modification factor, usually called the Ex-Mod, personalizes your rate based on your own loss history. A factor of 1.00 is average for your classification. A 0.80 modifier means you pay 20% less than the industry norm. A 1.50 modifier means 50% more.
The Workers’ Compensation Insurance Rating Bureau builds the factor from a defined experience period. That period begins four years and nine months before your rating effective date and ends one year and nine months before it.6WCIRB California. Experience Period In practice, that captures about three years of payroll and claims data, with a lag so older claims have time to develop to their real cost.
This is where the money is for most businesses over time. A single serious claim can lift your modifier above 1.00 for years, compounding across every renewal. Businesses whose modifiers stay high sometimes lose access to standard carriers and end up at the State Compensation Insurance Fund, the state’s largest workers’ compensation carrier and insurer of last resort.7State of California. State Compensation Insurance Fund
What Sits on Top of the Pure Premium Rate
The advisory pure premium rate covers only the expected cost of paying claims and adjusting losses. It does not include insurer overhead, agent commissions, taxes, profit, or state assessments. Two things get added before you see a final number.
The first is the insurer’s own loss cost multiplier. California uses an open-rating system, which means each carrier files its own rating plan with the Insurance Commissioner and sets its own price around the WCIRB’s advisory baseline.8California Legislative Information. California Code Insurance Code 11735 Rates must be adequate to cover the insurer’s losses and expenses under Insurance Code § 11732, but the law also prevents any single carrier (other than State Fund) from cornering the market.9California Legislative Information. California Code Insurance Code 11732 The practical effect is that two carriers can quote noticeably different prices for the same classification and Ex-Mod.
The second is the Workers’ Compensation Industry Assessment. For 2026, that surcharge is set at 5.191% of premium. It funds fraud investigations and the administrative machinery of the state’s workers’ compensation system, and it appears as a separate line on your policy.
Looking ahead to the next filing, the WCIRB has proposed advisory pure premium rates effective September 1, 2026 that average 10.4% higher than the current approved rates.10WCIRB California. WCIRB Bulletins If approved as filed, the statewide average would rise from $1.52 to roughly $1.68 per $100 of payroll.
Ways to Lower What You Pay
Your classification code is largely fixed by what your business does. The rest of the formula has more give.
- Drive down your Ex-Mod. Every claim you prevent keeps the modifier from climbing. An injury and illness prevention program, required under Cal/OSHA rules, is the foundation. Return-to-work programs that bring injured workers back in modified roles reduce the total cost of each claim, which lowers your modifier over the following years.
- Manage open claims. Review your loss runs regularly. Insurers sometimes carry inflated reserves on open claims, and those reserves feed the Ex-Mod calculation. Asking for reserve reviews and pushing to close claims when appropriate can prevent your modifier from drifting upward on paper losses.
- Ask about scheduled credits. Many carriers offer scheduled credits or debits of up to 25% (sometimes more) based on qualitative factors like safety programs, management cooperation, and premises condition. These adjustments sit on top of your Ex-Mod and are negotiable at renewal.
- Shop carriers. Because of open rating, prices for the same risk vary. Brokers who specialize in workers’ compensation can access multiple markets.
- Consider pay-as-you-go billing. Many insurers now tie premium payments to each payroll run instead of requiring a large upfront deposit. It does not change the total cost, but it improves cash flow and shrinks the size of the audit adjustment at year-end.
The Annual Audit
Workers’ compensation premiums begin as estimates based on projected payroll. After each policy period, the insurer audits your actual payroll and adjusts the premium up or down. Hire more workers than expected, or pay more overtime, and you’ll owe additional premium. Come in lower and you get a credit.
The WCIRB can also run test audits of insured employers within one year after a policy expires, checking the accuracy of both your records and the insurer’s own audit work.11California Legislative Information. California Code Insurance Code 11750.3 During any audit, the classification of every worker is verified. An employee who was coded clerical but actually spent time on job sites will be reclassified into the higher-rated code and the premium difference billed retroactively.
Keep detailed payroll records, time cards, job descriptions, and certificates of insurance for every subcontractor. Missing subcontractor certificates are the single most common source of surprise audit bills. Without them, the auditor treats the subcontractor’s payments as your payroll and charges premium as if those workers were your employees.
Owner and Officer Exemptions
Not everyone tied to a business has to be covered. Sole proprietors and business partners are not employees of their own company and are generally exempt. Corporate officers and directors in closely held corporations can opt out, as can managing members of an LLC. The exemption reaches only the owners themselves. If the business has even one non-owner employee, coverage for that employee is still required under Labor Code § 3700.12California Legislative Information. California Labor Code 3700
Licensed contractors handle exemptions through the Contractors State License Board’s online portal. Certain high-risk classifications cannot file an exemption at all. Contractors holding C-8 (Concrete), C-20 (HVAC), C-22 (Asbestos Abatement), C-39 (Roofing), or C-61/D-49 (Tree Service) licenses are ineligible.13CSLB. Workers Compensation Exemption Opting out saves premium on your own payroll, but it also leaves you without coverage if you’re hurt on the job. For owners who do physical work in hazardous trades, that trade-off deserves real thought.
The Cost of Going Without Coverage
California treats failure to carry workers’ compensation as a criminal matter. Labor Code § 3700 requires every employer to secure coverage, either from an authorized insurer or through a certificate of consent to self-insure.12California Legislative Information. California Labor Code 3700
Knowingly going uninsured is a misdemeanor under Labor Code § 3700.5. A first conviction carries up to one year in county jail and a fine of at least $10,000, or double the premium that should have been paid, whichever is greater. A second conviction raises the minimum fine to $50,000 or triple the owed premium.14California Legislative Information. California Labor Code 3700.5 The Division of Labor Standards Enforcement can also issue a stop order barring the business from using any employee labor until coverage is in place, and civil penalty assessments can reach $10,000 per employee on the payroll at the time of a compensable injury, up to $100,000 total.15California Department of Industrial Relations. DWC FAQs for Employers
The quietest consequence is often the worst. A properly insured employer benefits from exclusive remedy, meaning injured workers are limited to workers’ compensation benefits and cannot sue in civil court. An uninsured employer loses that shield. The worker can file a workers’ compensation claim and a civil lawsuit, exposing the business to damages well beyond what a policy would ever have cost.15California Department of Industrial Relations. DWC FAQs for Employers