The law
What Proposition 103 is
Proposition 103 was a 1988 California ballot initiative that changed how property and casualty insurance rates are regulated. For auto insurance, it moved California into a prior-approval system: a carrier has to file its rate plan with the California Department of Insurance before charging the new rates. It also made the Insurance Commissioner an elected position and gave consumer representatives a formal role in challenging rate filings.
The core auto rating rule is in California Insurance Code §1861.02. Rates for a private passenger auto policy must be built around the driver's safety record, annual miles driven, years of driving experience, and only those other optional factors the Commissioner permits by regulation. That rule is where a broker starts when checking a California auto premium.
The companion rate-approval rule is Insurance Code §1861.05. A rate cannot be approved or remain in effect if it is excessive, inadequate, unfairly discriminatory, or otherwise violates the chapter. The carrier has the burden of proving the rate change is justified. In many states, the question is often what the market will bear. In California, the question is what the filed data can support.
Prior approval
How CDI approval controls rate increases
A California auto insurance rate increase starts as a filing, not as a customer bill. The carrier submits rate pages, loss trends, expenses, underwriting rules, class-plan changes, and actuarial support. CDI reviews the filing under Prop 103 and the implementing regulations. If the filing is challenged by a qualified intervenor, the process can include data requests, settlement talks, and sometimes a hearing.
For the customer, the practical point is this: your carrier cannot legally invent a new statewide rate on the phone, but once a rate filing is approved, your renewal can still change sharply. The carrier is applying an approved plan to your specific household: garaging ZIP, vehicle symbol, drivers, miles, violations, coverage limits, deductibles, and discounts.
CDI's premium comparison tool is useful for seeing broad differences among companies, but it is not a quote. The final premium comes from the approved carrier plan applied to your exact risk. That is why two Westminster households with the same carrier can see different renewal changes.
Last Thursday, we reviewed a Westminster renewal where the approved filing was only part of the jump. The car was still rated at a Santa Ana garaging ZIP even though it had been sleeping near Magnolia and Bolsa for months. That was not a Prop 103 appeal. It was a correction to the facts inside the approved plan.
Mandatory factors
The three rating factors carriers must use
Driving safety record comes first. The carrier reviews public violation convictions from California DMV and similar out-of-state records, plus principally at-fault accidents under the California auto rating regulations. A DUI, reckless driving, at-fault crash, or multiple moving violations changes the pricing tier.
Annual miles driven comes next. California makes mileage central because miles are a controllable risk. Carriers can ask for expected annual mileage, commute details, odometer readings, and other support. If your commute changed after moving jobs, update it before renewal.
Years of driving experience is the third required factor.A newly licensed driver pays more than someone with a long licensing history, all else equal. For immigrants and AB60 clients, foreign driving experience sometimes helps only when the carrier's filed rules allow it and the documentation is clean.
California treats the file differently from many other states. Credit score is not the center of the file. Driving record, miles, and experience come first. That helps many households, but it also means a single bad record event can move the price hard because the system weights driving behavior heavily.
Optional factors
The 16 optional rating factors, and the 2026 gender rule
Older Prop 103 summaries often refer to the 16 optional rating factors in 10 CCR §2632.5. That phrase is still useful historically, but the 2026 working rule needs one correction: gender used to be listed, and CDI removed it effective January 1, 2019. CDI's gender non-discrimination regulation required auto carriers to eliminate gender as a rating factor.
For 2026, read the optional-factor list this way:
- Type of vehicle.
- Vehicle performance capabilities and alterations.
- Vehicle use, such as pleasure, commute, business, or farm use.
- Percentage use of the vehicle by the rated driver.
- Multi-vehicle household status.
- Academic standing of the rated driver.
- Driver training or defensive driving completion.
- Vehicle characteristics, including safety devices, repairability, and theft deterrents.
- Marital status of the rated driver.
- Persistency with the same carrier or affiliate, within the California limits.
- Non-smoker status.
- Secondary driver characteristics for certain unassigned drivers.
- Multi-policy status with the same or affiliated company.
- Relative claims frequency by garaging territory.
- Relative claims severity by garaging territory.
- Gender, the old factor, which carriers cannot use for California private passenger auto rating in 2026.
What carriers cannot use casually: credit score, race, national origin, immigration status, a made-up “agent judgment” surcharge, or an unfiled discount that is not part of the approved class plan. Occupation and education are also not blanket reasons to rewrite a premium at the counter. If a carrier uses a group, affinity, or academic rule, it has to fit its filed and approved structure.
Why rates feel high
Why California auto insurance is expensive even with Prop 103
Prop 103 does not freeze prices. It controls the proof process. California can have stable regulation and high premiums at the same time because the underlying costs are high: body-shop labor, parts delays, medical bills, litigation pressure, theft, catalytic converter losses, uninsured drivers, and dense traffic. Southern California adds another problem: the garaging ZIP can change the entire quote.
Timing creates most of the frustration. During periods when CDI slows or disputes rate approvals, carriers may restrict new business, tighten underwriting, or wait for approval. When approvals finally come through, consumers feel several years of loss-cost pressure at renewal. That is the plain answer to why California auto insurance is expensive: the state limits how rates are justified, but it does not make repair shops, hospitals, injury claims, or vehicle values cheaper.
In our office, the job is to separate a statewide California auto insurance rate increase from a household-specific problem. A statewide filing affects everyone in a carrier's book. A household problem might be wrong mileage, a driver assigned to the wrong car, a garaging ZIP error, a missing multi-policy discount, or a violation that should have aged out.
Recent battles
2024 to 2026 rate increase fights
Recent filings show the Prop 103 process in plain view: large carrier requests, CDI review, consumer intervention, and approved increases that still reach renewals. Allstate returned to direct California auto sales in 2024 after regulators allowed an average increase reported around 30% (illustrative per CDI 10 CCR §2030). Mercury's 2025 annual report says CDI approved a 22.5% (illustrative per CDI 10 CCR §2030) private passenger auto increase for Mercury Insurance Company and a 3.8% (illustrative per CDI 10 CCR §2030) increase for California Automobile Insurance Company in January 2024. State Farm Mutual Automobile Insurance Company filed in 2024 for a 23.4% (illustrative per CDI 10 CCR §2030) auto increase, then resolved at 17.7% (illustrative per CDI 10 CCR §2030) after intervention and review.
Those are not household discount conversations. They are statewide rate filings with actuarial exhibits, consumer challenges, and CDI review. That is why a broker cannot simply call Mercury, Allstate, or State Farm and ask them to ignore an approved rate. We can check whether your policy is classified correctly. We cannot veto the approved filing, and any broker who promises that is selling noise.
What consumers can do
How to appeal, correct, or negotiate your renewal
You cannot negotiate a filed California rate the way you negotiate a used car. You can challenge the facts being used to calculate your premium. Start with the declarations page and renewal packet. Confirm every driver, every vehicle, garaging address, annual mileage, commute use, coverage limit, deductible, lienholder, and discount.
- Correct mileage. If the carrier is using stale mileage, provide an odometer reading and current commute details.
- Correct garaging. The ZIP where the car sleeps most nights matters. Mailing address is not always garaging address.
- Correct driver assignment.The highest-risk driver should not be assigned to the highest-rated vehicle unless the carrier's filed rules require it.
- Ask for an underwriting review. If a ticket, accident, or claim is wrong, provide documents and ask the carrier to review the record.
- Shop admitted carriers. Prop 103 controls rate approval, but carriers still price differently inside their approved plans.
- File a CDI complaint if the carrier will not fix a clear error. CDI's Getting Help page explains how consumers can ask questions or file complaints.
Keep the tone boring and documented. Send the renewal, the page you think is wrong, and the proof. “My bill is too high” is not an appeal. “The policy uses 18,000 annual miles, but the odometer and commute support 7,200” is an underwriting correction request.
Common questions
Prop 103 auto insurance questions
Does Proposition 103 keep my premium from going up?
No. It requires the carrier to justify and receive approval for the rate plan. Your individual renewal can still rise when an approved filing takes effect or when your personal rating facts change.
Can a carrier use my credit score in California?
Not as a California private passenger auto rating factor. If you moved from another state, this is one of the biggest differences. California focuses on driving record, mileage, years licensed, vehicle, use, and approved optional factors.
Can my ZIP code affect my rate?
Yes. California allows territorial factors tied to relative claims frequency and severity. The ZIP must reflect where the car is garaged, not where mail is easiest. Wrong garaging can become a claim problem.
Why did my renewal increase if I had no tickets?
A statewide approved rate filing can move your premium even with a clean record. Also check vehicle symbol, repair cost, mileage, driver assignment, and discount changes.
Can a broker get around an approved rate?
No. A broker can shop carriers and correct classification errors. A broker cannot discount below the filed and approved carrier rate.
Should I lower coverage to offset a rate increase?
Sometimes, but do it carefully. Raising deductibles on an older paid-off car can make sense. Dropping liability too low can expose your wages, home equity, and savings after an at-fault crash.
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