Have you looked at your credit report recently? Of course you have — you’re a Marketplace Money listener! And that means you also know that you can get a copy of your credit report, every year, from each of the three credit rating agencies for free. And if getting something for free isn’t enough for you, here’s another reason: There’s a good chance that your credit report is not entirely accurate. The Federal Trade Commission released a report this week, saying more than a quarter of credit card-carrying Americans have at least one “potentially material error” in their data — that’s as many as 42 million consumers. John Ulzheimer is one of our credit go-to guys. He used to work in the credit rating business, for Equifax, and now he’s president of consumer education at SmartCredit.com.

“The report is a little troubling. Having said that, the 42 million potential credit reports with errors, there’s a little bit of silver lining to that — meaning that the errors can be anything from a misspelled former address, which is really meaningless to the world of credit risk assessment, to something more serious like a collection that doesn’t belong to the consumer or a late payment that didn’t actually happen. So it really underscores the importance of we the consumer becoming way more engaged with our credit reports to identify things that are wrong,” says Ulzheimer.

Ulzheimer says consumers should head to AnnualCreditReport.com to get their free credit report. He says the rules under the Fair Credit Reporting Act state that the credit reporting agencies have no liability until consumers identify that something’s wrong in their report. But the problem is that we’ve done a bad job of checking our credit reports. If you do find an error, Ulzheimer says to start the dispute process, you should communicate with the credit reporting agencies. Then the agencies have certain obligations.

How to dispute an error in your credit report. Check out these links to start:

Experian

Equifax

Transunion

“They must show the item in dispute that you’re challenging, which means that anybody who sees it from that point forward knows that it’s in question. Second, they have to identify through the furnishing party whether or not the item is correct or incorrect. And the furnishing party is almost always going to be a financial institution or a collection agency.” Ulzheimer said.

“They’re basically saying, ‘Hey look, John filed a dispute. He says this is wrong, you let us know. Was it right or wrong?’ And then they’re going to essentially pare it back to the consumer what they heard back from the furnishing party. Then you as the consumer can either live with it or if you’re dissatisfied with the mistake, you can go directly to the source yourself and take your argument up with them.”

Ulzheimer says the frustrating thing about this process is that “the credit reporting agencies are always going to take the word of the bank or the collection agency over the word of the consumer.” Ulzheimer advises consumers to be as plugged in to the data on your credit report as you are with the charges on your credit cards. He also encourages consumers to leverage their federal rights (like getting your free credit reports and the ability to get items corrected), take their battle to the bureaus if they think something is wrong, and seek out a consumer advocate attorney if you’ve really been damaged by the error.