How Car Insurance Rates Are Calculated

How is my car insurance price decided?

You got a quote and you are wondering where the number came from. Here is the short version. Every insurer has a base price for your state, built from what it expects to pay in claims. Then it moves that price up or down for you. Your driving record, where you park, what you drive, how far you drive and the coverage you pick all count.

Two words are worth knowing. A rate is the price of one slice of coverage, such as one car for one year. Your premium is what you pay once the company applies that rate to your policy. Each company uses its own formula, so two insurers can price the same driver very differently. That gap is why comparing quotes pays off. For actual dollar amounts, see how much car insurance costs.

Some price changes have nothing to do with you. Cars, parts and repairs cost insurers more. Crashes get costlier when driving gets riskier. Storms hit. Insurers also buy insurance for themselves, called reinsurance, and that has a price too. All of it flows into everyone’s rates.

Which factors change my price the most?

Every company’s list is a little different. These show up almost everywhere:

• Your driving record. At-fault crashes and tickets on your motor vehicle report push the price up. If the report has a mistake, it costs you money.
• How much you drive. Miles per year, and whether you commute or drive for fun.
• Where the car is kept. Your ZIP code or neighborhood, based on how often and how expensively people there file claims.
• The car. Its type, speed, safety and anti-theft features, and what it costs to repair or replace.
• Who you are. Age, marital status and job are common. Gender is a common factor in Texas, but California bars it. A 2019 news report named Massachusetts, Michigan, Montana, North Carolina and Pennsylvania as other states that bar it. Laws change, so check yours.
• Your credit history, in most states. More on that below.
• Loyalty and bundling. Time with the same company, or more than one car or policy.

California is the one state we found that ranks the factors by law. Your driving record must count most, then your annual miles, then your years of driving experience. Every optional factor, such as ZIP code or car type, must count less than all three. So in California your ZIP code cannot outweigh your record. Elsewhere, each company’s filed plan decides.

How do those factors turn into a price?

Picture a standard price with a multiplier for each factor. A multiplier of 1.00 means average. A multiplier of 1.20 means a group expected to cost about 20% more in claims.

Here is an example with made-up numbers, not taken from any real filing. Your area scores 1.10 because claims run a bit higher there. Your driver group scores 0.90 because of your clean record. Your car scores 1.25 because it is costly to repair. Multiply them and you get 1.2375. Your price lands about 24% above the company’s standard price.

Now change one piece. If you switch to a cheaper-to-repair car, the 1.25 drops and so does your total. A different company has different multipliers, so it will land somewhere else.

Does the state approve car insurance rates before I am charged?

It depends on your state, but no state leaves prices unchecked. Insurance is regulated by the states, not by Washington, so the rules differ across the map. The NAIC, the group of state insurance regulators, sorts states into a few types:

• Approval first. The company waits for the state’s OK, or for a waiting period to pass. California, New York, Pennsylvania, New Jersey and North Carolina work this way.
• File and use. The company files its new rates, then starts using them. The state can still object later. Texas lets a company use a new rate the day it files. Michigan makes it wait up to 90 days. Florida lets the company choose between this and the next type.
• Use and file. The company starts charging first and files soon after. Illinois requires filing within 10 days.

All of these share one legal test. A rate may not be too high, too low to pay claims, or unfairly discriminatory. In Florida, two drivers in the same group cannot be charged different prices unless the gap tracks real differences in expected claims and costs. Texas also bars rates based on race, creed, color, ethnicity or national origin.

What does that mean for you? Approval is not a promise that your price is the lowest one available. The Texas department says it does not set rates. It reviews the analysis behind each filing and asks questions. Your best protection is still a side-by-side comparison. The details table near the end shows the waiting periods.

Can my insurer use my credit score to set my price?

In most states, yes, with limits. According to NAIC’s chart, Massachusetts, Michigan and Hawaii bar it for auto pricing. California’s list of allowed factors leaves it out too.

An insurance score is built from your credit file, but it is not the score your lender sees. It looks at how many accounts you have, how much you owe, late payments, the age of your oldest and newest accounts, and recent credit applications. A 2007 federal study found these scores do predict risk on auto policies. It also found they differ across racial and ethnic groups, which likely affects average premiums for those groups. The researchers could not build a model that predicted as well and narrowed those gaps.

Where credit is allowed, you still have protections:

• Not the only reason. Texas and Florida say credit cannot be the only reason for a bad decision against you, such as a refusal, cancellation or non-renewal. Both make room for life events such as divorce or job loss.
• Reasons in writing. In Texas, if credit played a part in a bad outcome for you (a refusal or a higher price, for example), the company must send the reasons within 30 days.
• A fresh look. For Texas policies issued or renewed since January 1, 2026, you can ask for a new review at renewal once a year. Credit must also generally be refreshed, and your price re-rated, at least every three years.
• A federal floor. If credit helped cause a price increase, the company must tell you. It must name the credit bureau and say the bureau did not make the decision. You can get a free copy of your report within 60 days and dispute errors.

Our credit and car insurance guide goes deeper. One note on sources: we read the California rule and the Texas, Florida and federal texts directly. The Massachusetts, Michigan and Hawaii bans rest on NAIC’s chart because those state sites blocked us. Confirm them with your state department.

Do mileage and driving apps change my price?

They can. Telematics means pricing on how you actually drive, such as miles, braking, speed and time of day. An app, a plug-in device or the car itself collects the data. A consumer-group letter to NAIC in January 2025 argued that most states have few or no safeguards on that data. That is an advocacy claim, but it is a good reason to read the terms.

California shows what a rule can look like. If a company also offers a mileage-estimate option, joining the tracked program must be voluntary. Any discount must rest on real cost savings. A device may record miles, but not where the car has been, with limited exceptions such as emergency road service and theft recovery.

Before you sign up anywhere, ask four things:

1. What data does it collect?
2. Can it raise my price, or only earn a discount?
3. How long is the data kept?
4. Is it shared with anyone else?

Why did my price go up when I made no claims?

Usually something changed that is not about your claims. Factors that move between renewals, such as your car’s value, can raise or lower the price. On top of that come the costs that hit everyone: repairs, costlier crashes, bad weather and reinsurance.

The Texas department says it has no information on any single policy. So your company is the one that can explain your increase. Ask which factors changed and what discounts you are not getting. If the rise came after a crash, see rate increases after an accident.

How do I look up my insurer’s rate filing?

Filings are public in many states, though they are dense. Look one up if you want to know why a company is raising prices.

1. Use the right name. Search the legal company name on your policy or bill, not the agency that sold it.
2. Use your regulator’s search. Texas shows the product name, the date received and the estimated percent change. “Reviewed” means the state closed its review. “Withdrawn” means the company pulled the filing.
3. Open the full filing. Many states use NAIC’s SERFF Filing Access. Only public filings appear. Confidential documents stay hidden.
4. Find two pages. Georgia’s guide says the “Rate Information” page shows the change as first submitted. The “Disposition” page shows the final result. They often differ, so use the latest Disposition.
5. Treat the percentage as an average. Texas says the effect on any one policyholder can be higher or lower.

What to do next

1. Check your motor vehicle report. Your driving record often counts most. Fix any errors with your state’s motor vehicle agency before you shop.
2. Confirm your mileage. If you drive less than the company assumes, tell it.
3. Get three quotes with identical limits and deductibles. Different coverage makes quotes impossible to compare. Our quote-reading guide shows how.
4. Ask your current insurer what changed and which discounts you are missing. Our guide to lowering your premium lists ideas.
5. If credit may be a factor, ask for the notice and the reasons. Where your state allows it, ask for a fresh review.
6. If you suspect a banned factor, call your state insurance department. Texas drivers can start at the Texas auto insurance page.

The details in one table

NAIC says its chart is not a legal opinion and that the underlying laws control.

Bottom line

If your price looks high, fix what you control first. Check your record, confirm your mileage and compare three quotes at the same coverage. If a credit check raised it, ask for the notice and the reasons. If you think a banned factor was used, call your state insurance department. The formula belongs to the insurer. The inputs, and the choice to shop around, belong to you.