I first met Edith Calzado at a place in New York City where low-income people can get free financial counseling. When she started talking to her counselor, Edith seemed to be in pretty bad shape.
She was a single mother of a young son, and she had a restraining order against her abusive husband. She was making about $16,000 a year, and she had $2,300 in debt.
But as the counselor asked more questions, the picture began to brighten. All that debt, it turns out, is interest free. You know how banks offer those teaser zero percent interest rates? Edith milks them for all they're worth.
It turns out, not every transaction between a poor person and a credit-card company ends up with the credit-card company on top.
Edith says she's borrowed about $13,000 from Citibank this way, and has never paid interest (though she does pay a balance-transfer fee of 3 percent).
Recently, one of these interest-free loans allowed Edith to treat her son Sammy to something he'd never experienced before: a vacation at a resort in the Dominican Republic.
"I paid $103 dollars for my son and I, everything included, from Friday to Saturday," she said. "My son said, 'Awesome!' "
"We also went to Ocean World," Sammy says. "I got to dance with a dolphin."
And the cost of dancing with that dolphin, thanks to Citibank, Edith can now spread out over the next year in interest-free monthly installments.
She's also good at signing up for those store credit cards -- the ones where they give you 10 percent off your purchase -- then quickly paying off the balance and closing the card.
Sears, Toys R Us, the Gap, Old Navy, Wal-Mart: Edith has opened and closed cards at those stores before the companies that issue the cards could make a cent off her. She's taking their money, not the other way around.
Now, it's a special kind of thrifty person who can pull this off.
Even though Edith lives at the poverty level, she puts money into a savings account every month. She gives 10 percent of her wages to her church every week. And she doesn't splurge often: She still wears the same pair of shoes she wore when she arrived in this country, in 1997.