Your salary

Salaries haven't "been on a report since the early 1990s," says John Ulzheimer, president of consumer education for SmartCredit.com. Even then, it was "highly dubious" because the information came from the consumers themselves, he adds.

If you ask someone what they will make this year, there are "too many variables," such as layoffs, raises, commissions and bonuses to get an accurate answer, says Ulzheimer.

Another reason you won't see salaries on credit reports: "Income really isn't a measure of creditworthiness," he says. "It's a measure of capacity."

Your credit report and your credit scores are meant to tell "a creditor whether or not you're going to make a payment, not whether you can make a payment," Ulzheimer says.

Other income sources that also don't appear on your credit report: unemployment benefits, alimony, child support or public assistance.