You’re ready to buy a car. You sit down with your car dealer’s financing guy and you’re told the interest rate of your auto loan is affected by your credit score. You’re not surprised.

But when you go to insure that car, you are surprised to find that your credit history can also influence the amount of your monthly premium.

In Maine, as in most states, insurance companies can and do take into account a customer’s credit information when calculating the cost of an auto policy.

Only three states have passed laws barring the use of credit scores by insurance companies to affect the cost of auto insurance: California, Hawaii and Massachusetts.

A national consumer watchdog group is hoping to spread that ban to all states.

According to the Maine Department of Professional and Financial Regulation, “many personal auto and homeowners insurance companies look at consumer credit information to decide: whether to issue or renew an insurance policy and how much premium to charge for insurance.”

The website explains that, according to state and federal law, insurance companies don’t need permission from consumers to search their credit backgrounds.

If you don’t know whether your insurance company is using your credit information for eligibility or to adjust your premium, you can ask your agent or the company.

You also might want to ask whether the agent or insurance company checks the credit history of other people named on your policy, such as family members and how that information may affect your policy, according to the state’s website.

“In Maine, an insurer can’t base your renewal rates only on credit history,” the department’s website says. “Other factors like your driving record or any claims that you have had must also be considered along with your credit history.”

If an insured motorist has worked to improve his or her credit, that motorist can tell the insurer to re-evaluate his or her premiums, according to Doug Dunbar, a spokesman at the state department overseeing insurance regulation.

According to the website Wallethub, auto insurance premiums in Maine can fluctuate by 70 percent, among the higher in the nation, topping out in Michigan at 115 percent. The lowest rate of fluctuation is seen in Connecticut at 15 percent, where credit information has the least affect on premiums, the Wallethub study reports.

Farmers Insurance relies most heavily on credit data; Geico, the least, of five major national insurers looked at, according to that study.

Robert Hunter, who oversees insurance issues at the Washington-based Consumer Federation of America, said his organization opposes the practice by insurance companies and is working at banning the practice nationally.

“It’s not fair,” Hunter said, adding, “It undermines safety.”

Hunter said credit scores can be the most important factor when an insurance company calculates a car owner’s premium, assigning them greater importance even than drunken-driving convictions and citations for moving violations.

That sends the wrong message to motorists, he said.

The practice is especially unfair in states (all but New Hampshire) where auto insurance is mandated, putting even more at risk the livlihoods of people who may already be struggling financially.

And it’s not just the largest national insurers who use credit information to affect premiums. More than 90 percent of auto insurers, including regional companies, engage in the practice, he said.

Phone calls to insurance companies and insurance agencies were not returned.

A federal ban is unlikely, Hunter said.

His organization is gearing up to tackle the issue state by state, including Maine, where Hunter said he spends his summers.

cwilliams@sunjournal.com