A Credit Score You've Earned

No question, piggybacking has helped some consumers. But borrowing someone else's good credit history doesn't always have a happy ending.

I've heard my share of horror stories from people who allowed a relative or friend to become an authorized user only to be left with major debt. Or the authorized user, who was responsible for paying the bill, didn't make payments on time, thus ruining the primary cardholder's good credit name.

Being an authorized user doesn't give someone a chance to demonstrate that he or she can actually use credit wisely. In fact, that's why in creating their own credit scoring system, VantageScore, the three major credit bureaus didn't included authorized users in calculating a person's creditworthiness, according to Lisa Zarikian, who leads Equifax Predictive Sciences and was a member of the team that created the scoring system.

Although Fair Isaac is updating its scoring model, piggybacking will continue for now because not all lenders will immediately change over to the updated FICO version.

I understand the desire to want to help someone qualify for credit or get the best loan deal. But that person's inability to qualify for credit could be a good thing. Just because someone wants credit doesn't mean the person can afford it. That's why the individual didn't qualify in the first place. Maybe he or she isn't ready for the responsibility.

And consider this: If you never meant to allow an authorized user to use your card, you're complicit in helping someone misrepresent themselves as creditworthy. Bottom line: This is unethical, whether it's being done by somebody's mama, daddy, friend or stranger.

· On the air: Michelle Singletary discusses personal finance Tuesdays on NPR's "Day to Day" program and online athttp://www.npr.org.

· By mail: Readers can write to her at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.

· By e-mail:singletarym@washpost.com.

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