Dear Liz: I bought my credit score from one of the big-three credit bureaus, but when I applied for a loan I learned my "real" score was much lower. Why are the bureaus allowed to sell fake scores?

Many consumers don't realize there's more than one credit-scoring formula. In addition to the well-known FICO score, each of the three credit-reporting bureaus — Equifax, Experian, and TransUnion — sells so-called consumer-education scores. Then there's VantageScore, a FICO rival developed by all three bureaus that uses a scale ranging up to 990 points (the top FICO is 850). Critics often call these upstarts "FAKO" scores, because most lenders currently judge your creditworthiness using the FICO.

See also: Don't fall for free credit report scams.

The bureaus say a credit score is a credit score, so it doesn't matter which one you get. But it matters to them: When bureaus sell their own scores, they don't pay royalties to the Fair Isaac Corporation, which owns the proprietary FICO formula. Fortunately for consumers, a law that takes effect July 21 will clarify the difference among the scores. The new regulations say that if you don't get the best terms on a loan, credit card, insurance policy, or utility service, you must be shown — for free — the score used to judge you. And most scores revealed will be some version of the FICO.

Next: How to get insurance when your credit score is low. >>