WEST PALM BEACH, Fla. -- Whether drivers know it or not, they're playing an insurance game in which what they pay depends partly on a score they typically never see.

WEST PALM BEACH, Fla. -- Whether drivers know it or not, they're playing an insurance game in which what they pay depends partly on a score they typically never see.

It's kind of like being forced to wager on a sporting event but sitting in a seat where you can't see the action or the scoreboard. It can make you a little skeptical when the insurer says sorry, the score went against you and you owe more money.

Philip Haas said his car insurance premium from The Hartford went up about 25 percent, partly because the company said his "insurance score" changed.

He and his wife have clean driving records, no accidents, no DUIs, the Palm Beach resident said. But he found few answers: He was referred to credit bureaus, who said talk to the insurer, which didn't immediately respond to his queries.

He wonders what recourse he might have.

At the top of the list: Shop around. A premium increase of 25 percent is an invitation to find out what other insurers would charge. One starting point is the state's Choices website, or talk to agents, or there's also a thriving community of websites that let you comparison-shop. An example is bankrate.com of North Palm Beach.

Another thought is to find out more about your insurance score and how to influence it. One option: Creditkarma.com is a free site that lists, among other things, your car insurance score from credit bureau TransUnion.

This score is not identical to your regular credit report, but it draws on some of the same information and ranges from 150 to 950, creditkarma explains: "It is calculated using data from your TransUnion credit report and is used primarily by auto insurance companies to help assess the likelihood that you'll file an insurance claim. It is not based on your driving record."

Insurers may use their own formulas they don't necessarily share with the public, but a common element in them is data that is supposed to measure how good you are at paying your bills. Since the 1990s, this has become an increasingly common practice by insurance companies.

By 2001, 92 percent of insurance companies were using credit information to help set premiums and choose customers, according to studies cited by insurer Progressive. As of 2006, all of the top five auto insurers did so.

''Like other insurers, Progressive uses insurance scores and other underwriting tools and rating variables to place customers in groups, determine potential insurance claims risk for those groups, and calculate accurate rates based on the potential risk that each group represents," a company website says.

Why insurers do it

Insurers defend doing this because they say research shows certain characteristics such as a good credit report correlate strongly to people who are less likely to file a claim. Consumer groups say it can be unfair to excellent drivers who don't happen to have strong credit records, or whose credit reports are marred by errors they don't know about. Skeptics also say it can be a backdoor way for insurers to favor drivers who are working or have higher incomes, something they're not supposed to do.

''Some of these factors, individually and in aggregate, may be surrogates for income, a factor forbidden from use in all states," a Consumer Federation of America report said.

Still, if you're a driver with a decent credit record, all this might be OK with you so far. But what if you're a responsible driver and bill-payer, and you're not aware of any recent problems in your driving or financial life, but your insurance score mysteriously goes down?

It can be tough to get insurers to say directly what goes into their formulas -- and whether entering certain age brackets, for example, can affect your insurance score. Haas happened to reach a birthday ending in a zero this year, and so did I. I noticed my own insurance score went down slightly on creditkarma.com this month after being unchanged for a long stretch.

''The Hartford uses components of an individual's credit history, which is then formulated into an insurance score according to our model, which is filed with the Florida Office of Insurance Regulation and notices are sent to our customers when required," said Hartford spokeswoman Heather Serignese. "We are continuously re-evaluating our rates and adjust periodically to ensure our pricing adequately covers the risk of doing business in Florida."

State Farm's practice

State Farm uses insurance scores to help determine premiums and coverage for new customers, but not existing ones, spokeswoman Michal Brower said.

''While we wouldn't share the specifics of the exact types of factors we use for proprietary business reasons, I can share that we take into consideration the characteristics that are most predictive of insurance risk," Brower said.

Here's what TransUnion spokesman Clifton O'Neal said: "It's important to know that an insurance score differs somewhat from a traditional credit score. For one, the score range is different than a regular credit score. The biggest difference is that the formula used to arrive at the score is designed specifically to assess your likelihood of filing an insurance claim. As a result, insurance scores are largely based on how well you have paid your credit over a period of time -- so that history plays a key role in determining your insurance score."

Factors that go into TransUnion's proprietary TrueRisk insurance score include recent delinquencies, oldest transactions, auto transactions, number of credit inquiries and more, he said.

Under federal law, a consumer is allowed to see his or her regular credit report free once a year from the three major credit reporting bureaus through www.annualcreditreport.com.

But what about insurance scores? A spokesman for the federal Consumer Financial Protection Bureau had no immediate information, but O'Neal said he could not let me see a report on my own TransUnion insurance score, for example.

State regulations impose some requirements on insurers, said Amy Bogner, a spokeswoman for the Florida Office of Insurance Regulation.

When the use of a credit score results in an "adverse decision," the insurer most provide notification to the consumer explaining why, Bogner said. The reasons must be provided in "sufficiently clear and specific language so that a person can identify the basis for the insurer's adverse decision," she said. "Such notification shall include a description of the four primary reasons, or such fewer number as existed, which were the primary influences of the adverse decision."

Haas, for one, wasn't feeling satisfied as to the explanation he got.

Bogner had one final piece of advice: "The consumer may also want to contact the Department of Financial Services Division of Consumer Services to either file a complaint or discuss this matter in more detail. They can be reached toll-free in Florida at 877-693-5236."

Charles Elmore writes for The Palm Beach Post. E-mail: charles(underscore)elmore(at)pbpost.com.

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