When people ask why California insurance works differently from other states, the answer usually starts with Proposition 103. Voters approved it in November 1988, and it still controls how auto, home and most other property and casualty insurance rates are set. In 2026, Prop 103 is back in the headlines because of a fight over the public intervention process and a new Insurance Commissioner who campaigned on consumer protection.
This guide explains the basics in plain language: what Prop 103 does, how a rate request moves through the system, what factors affect your auto insurance premium, and why the 2026 debate matters to you.
What Prop 103 does
Prior approval. Insurers must get approval from the California Department of Insurance before changing rates for covered lines, including private passenger auto and homeowners insurance.
An elected Commissioner. Prop 103 made the Insurance Commissioner an elected office, which is why voters chose a new Commissioner in 2026.
Public participation. Any member of the public can challenge a rate request, and qualified intervenors can be paid for their work if they make a substantial contribution to the decision.
Auto rating rules. For personal auto insurance, the most important rating factors must be your driving safety record, miles driven per year, and years of driving experience.
Good driver discount. Drivers who qualify as good drivers must receive a discount of at least 20 percent.
Prop 103 also led to the rollback of rates in the late 1980s and gave the Department broad authority to regulate how insurers price and sell policies.
A quick history
Prop 103 passed narrowly in 1988 after years of steep auto premium increases. Insurers challenged it in court, and the California Supreme Court upheld most of it in 1989. Over the following decades, the Department and the courts filled in the details through regulations and decisions. Supporters credit the measure with keeping California auto rates closer to the national average than they were before 1988. Critics argue that the same rules made it harder to adjust rates quickly when wildfire losses rose. Both views shape the debate today, and both are worth understanding before forming an opinion about proposed reforms. Our article on the California insurance crisis covers how the property market reached this point.
How a rate request moves through the system
The filing. An insurer submits a rate application with data on losses, expenses, projected costs and, increasingly, catastrophe modeling and reinsurance.
Public notice. The application becomes public, and consumers may request a hearing. For personal lines, a hearing must be granted on request if the increase exceeds 7 percent.
Review and intervention. Department actuaries review the filing. Intervenors may submit their own analysis arguing that the request is too high.
Decision or settlement. The Department approves, modifies or rejects the request, often after negotiation. Settlements frequently reduce the requested increase.
Effective date. Approved rates apply to new policies and renewals after the stated date.
That process explains why it can take many months between an insurer's request and a change on your bill. Recent examples include the FAIR Plan's 29.1 percent average increase, approved below the 35.8 percent requested, and the State Farm homeowners settlement.
What affects your auto premium in California
Because Prop 103 prioritizes driving record, mileage and experience, your own behavior matters more in California than in many states. California also does not allow insurers to use credit history or credit scores when rating personal auto policies. Other factors insurers may use, within approved rules, include the vehicle, coverage limits, deductibles and where the car is garaged.
That has practical consequences:
A clean record over several years can earn the good driver discount.
Low annual mileage can lower your price, so report mileage accurately.
Tickets, at-fault accidents and DUIs can raise rates sharply; a DUI may also require an SR-22 filing. Our guide to high-risk driver insurance explains options.
Your choice of limits matters, especially since the minimum rose to 30/60/15 in 2025.
What affects your home premium
For homeowners insurance, insurers use approved rating plans that consider the home's location, construction, age, roof, protection class, claims history and coverage choices. Under the Sustainable Insurance Strategy, insurers that meet certain availability commitments may now use wildfire catastrophe models and reinsurance costs in their filings, and those models must recognize mitigation. Insurers must also offer Safer from Wildfires discounts.
The 2026 intervenor debate
Intervenors are at the center of the current political fight. Supporters of the system, including Consumer Watchdog and dozens of consumer groups, say intervenors have saved Californians billions of dollars by challenging excessive rate requests, and that the threat of intervention keeps filings honest. In 2026, 32 groups urged the Department to withdraw proposed changes, arguing they would weaken consumer protections.
The Department under Commissioner Ricardo Lara describes its proposal as the first comprehensive modernization of the intervenor system since 1988. Its stated goals include more public reporting on intervenor activity and compensation, clearer timelines, and faster decisions so that insurers can price risk and keep writing policies. Insurers have generally argued that slow approvals contributed to companies limiting new business.
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Both sides say they want more available, affordable coverage. The disagreement is about whether faster, more predictable rate reviews or stronger outside challenges do more to achieve that. Commissioner-elect Jane Kim, who takes office in January 2027, will inherit the issue, and any final rules can be revisited through the formal rulemaking process.
Why this matters for your next renewal
Most policyholders will never attend a rate hearing, but the system still shapes your price. When you see a rate change on a renewal, it reflects a filing that the Department approved. You can look up public information about filings and decisions on the Department's website. You can also compare how different insurers price the same coverage, because each company has its own approved rating plan. That is why getting multiple quotes through an independent agent can make such a difference.
Prop 103 and businesses
Many commercial lines are also subject to prior approval, though some specialty coverages and surplus lines policies are not. If you own a business, your commercial insurance, commercial auto and workers' compensation pricing each follow their own rules. Workers' compensation, for example, has a separate rating system and is not set through the same Prop 103 process.
Common myths
"Prop 103 freezes rates." It does not. Rates can rise or fall, but changes must be justified and approved.
"My ZIP code sets my auto rate." Location can be a factor, but California requires driving record, mileage and experience to carry the most weight.
"Intervenors set prices." The Department decides. Intervenors present evidence and argument.
Frequently asked questions
Does Prop 103 apply to all insurance?
It applies to most property and casualty lines, including auto and homeowners. Some lines, like workers' compensation and life and health insurance, follow different rules.
Can my insurer raise my rate without approval?
Insurers cannot change the approved rates for covered lines without approval. Your premium can still change because of your own factors, like a new ticket, a new car or different coverage.
What is the good driver discount?
Drivers who meet California's good driver criteria must receive at least a 20 percent discount on qualifying auto coverage.
Can I challenge a rate increase?
Members of the public can participate in rate proceedings, and anyone can file a consumer complaint with the Department.
Who decides the intervenor rules?
The Department of Insurance through formal rulemaking, subject to the voter-approved text of Prop 103.
This is general information, not legal advice.
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