For many consumers, fixing a credit-report error — perhaps a payment mistakenly marked late — is an easy process. Others aren't so lucky.

Some consumers spend years disputing errors that stubbornly remain, often resulting in higher interest rates on loans or the inability to get credit at all, consumer advocates say.

Such errors arise for various reasons. The creditor may report incorrect information to the credit bureau that creates the report. Or the credit bureau may accidentally tie together two consumers' credit files when a consumer or employee inputs one wrong digit in a Social Security number. Then there's identity theft: A deliberate effort to feed off someone else's good credit record.

Critics of the system under which credit errors are disputed say problems are widespread. U.S. Rep. Barney Frank, D-Mass., chairman of the House Financial Services Committee, plans to hold hearings on the subject in March.

Credit bureaus say problems are rare. "There are times when there are some complications that may cause it to be difficult for a consumer, but literally millions of consumers contact us ... and everything gets resolved very easily," said Maxine Sweet, vice president of public education at credit bureau Experian.

But the problems can be big, noted Evan Hendricks, Washington-based publisher of Privacy Times, a newsletter on credit issues, and author of "Credit Scores and Credit Reports."

System faulted

In a recent case, a jury awarded hundreds of thousands of dollars to a victim, he said. "A hospital worker stole her identity while she was delivering her baby," he said. The victim "sent in a great dispute package, all the documentation, including the newspaper article of the thief getting sentenced, and they still couldn't correct her credit report."

"If the system works the way it's supposed to, it's great," Hendricks said. "The problem is it sometimes doesn't work."

Here's what should happen: If you see an incorrect item on your credit report, you dispute it with the credit-reporting bureau, either by telephone, in writing or online. The bureau then has 30 days to 45 days to verify or correct the information. If it can't verify the data, the law requires the item be removed.

But some consumers find erroneous items come back as "verified" and remain on the report.

Critics say an automated process is part of the problem. Consumers may mail in an explanatory letter and documents to prove their point, but the credit bureau usually converts that paperwork to a numerical code — and a lot can get lost in the translation.

The credit bureau sends that code to the creditor. The creditor checks its system and sees that it did indeed report that consumer as, say, 60 days late on a payment.

"They're usually just going to do this two-dimensional look at what they've done before," Hendricks said, often finding that "yes, this is what we've reported before."

Plus, he said, credit bureaus tend to favor creditors' claims over consumers, so if the creditor says "'we reported her as late; we're verifying that,' the credit reporting agency stops right there. Even if you sent in your cancelled check, it's hard to get them to look at stuff like that."

Tips to get it right

Review all three credit reports. You'll need reports from each of the three main bureaus — Experian, Equifax and TransUnion — to start the process. You can get one report from each bureau free once per year at http://www.annualcreditreport.com. If the system won't let you sign on, it may mean your security-question responses don't match that bureau's records (for instance, different street numbers for an old address). If so, write to the bureau for your report and send proof of your ID, including a copy of your driver's license and utility bill with current address, Sweet said.

Start your dispute with the credit bureau. To retain all their legal rights, "consumers should dispute inaccurate information directly with the credit-reporting agency," said Ian Lyngklip, co-chair of the National Association of Consumer Advocates and an attorney with Lyngklip & Taub Consumer Law Group in Southfield, Mich. Contact the creditor too. "Carbon-copy that dispute to the creditor that's putting the inaccurate information on your report, along with a cover letter," Lyngklip said. The letter to the credit bureau says, "I'm disputing the account with ABC Finance Company. Here's my proof that the item is inaccurate. Please have this corrected," he said. To the creditor, write "I just disputed this with the credit-reporting agencies. Here's a copy of the letter I sent to them. I'm also disputing this directly with you," he said.

Monitor credit reports for even minor errors. In some cases, a small error might be a sign of identity theft, Lyngklip said. "If you see a post office box [address] you've never seen before, you should be concerned because somebody might have used your name and Social Security number to create that mailbox." In other cases, Hendricks said, it's OK to ignore small errors if they're not affecting your ability to secure credit.

Maintain records of the dispute. Send mail "return receipt requested," keep copies of everything you mail, make note of telephone calls made and, if you file your dispute online, print out the Web site pages so you have records.

Be patient. The dispute process can take months, particularly if there's more than one error. If you're about to apply for a mortgage, consider asking your lender to help you work with the credit bureau to get the errors removed.

Consider a lawyer. If you can't get your errors resolved and they're hurting your financial life, consider a lawyer.