long time without using a credit card

•Retirees. If they've gone a long time without using a credit card and the mortgage is paid off, they may have little or no credit history, says Watts.

•Older widows and divorcees. If a couple routinely kept the mortgage, bills and credit cards in the husband's name and he dies or leaves, the woman is starting with a blank slate. But this situation is much less common than it was 30 years ago, according to credit experts. "Most people know to have both names on the account, so that it appears on her history," says Sweet.

•Those who purposely abstain from seeking credit. For some people, the decision to live without credit is voluntary and not an accident or matter of temporary circumstance. "They might have philosophical, political or religious reasons" for living a cash-only life, says Watts.