Getting a "free" credit report can end up costing you.Plenty of TV, radio and Internet ads promise consumers a copy of their free credit report, but what the companies behind those ads really want is to entice you into signing up for "credit monitoring" or other services. And those are decidedly not free, running anywhere from $15 to $30 a month or more on your credit card bill.Sacramento, Calif., retiree Jim Fossum found out the hard way.In May, he thought he was going online to ask for a free copy of his credit report from AnnualCreditReport.com — the official website for such requests. He got the report but was startled when a $29.95 monthly charge popped up on his next credit card bill."I got sucked into something I didn't want," said Fossum, 82, who isn't sure how he wound up on a different site, GoldenScoresLLC.com, which started charging him for monthly credit monitoring.Fossum's experience comes after a much-publicized Federal Trade Commission case in 2005 against FreeCreditReport.com. Accused of using deceptive tactics, FreeCreditReport was fined more than $1.2 million by the FTC.There's only one website that is federally authorized to provide consumers with free annual credit reports: AnnualCreditReport.com. By law, everyone is entitled to a free credit report once a year from each of the three credit reporting bureaus: Equifax, Experian and TransUnion.In addition to the official AnnualCreditReport.com site, several companies will give you a free credit report, an estimated credit score or both, including Bankrate.com, Credit.com, CreditKarma.com and CreditSesame.com.The FTC says some sites use terms such as "free report" in their names. Others have URLs that purposely misspell "AnnualCreditReport.com," hoping you will mistakenly type in their name.In some cases, the "free" product requires that you provide a credit card number, which is used to enroll you in a trial membership for various credit monitoring services.