At first glance, the rules for fixing an error seem simple enough. But because merchants or lenders don't necessarily report to all three credit bureaus, a mistake might appear on one, two or all three of your reports, and you must dispute each one separately.

You can get a free copy of your credit reports at the three major credit bureaus, Equifax, Experian and TransUnion, once a year at AnnualCreditReport.com. You can also get a free report if you've been denied credit based on information in your report.

As long as the credit bureaus comply with the Fair Credit Reporting Act and verify that they're correctly reporting the information they received from a lender, they consider their job to be done. So your first call should be to the company who reported the problem. When you have enough information to disprove theinformation and to correct the mistake, start your challenge.

Each credit report has a phone number as well as an address to start a dispute, or you can do so online at transunion, equifax or experian. However, if the report is more than 60 days old, you likely will have to get a new report to begin a protest.  Also, if you got your report from a third-party site rather than directly from the credit bureau, you may have to get a report from the bureau to begin your challenge (but it's supposed to be free).

Bureaus typically have 30 to 45 days to "resolve" your dispute. If it's a simple factual error that is acknowledged by the lender, it could take as little as two weeks. You will be notified of the bureau's decision via regular mail or e-mail.