Mark Winslow, a medical physicist from Upland, Calif., was in no rush for his refund when he walked into H&R Block a couple of years ago to have his taxes prepared. So he declined the tax preparer's offer of a so-called quick loan to tide him over until the Internal Revenue Service check arrived.

"I thought the interest rate was outrageous," Winslow, 37, said of the annual interest rate of more than 19 percent, on top of a processing fee.