6 ways to kill your credit score

Sending in your loan or credit card payments late can really hurt.

Rex Johnson, founder of credit union consulting firm Lending Solutions Consulting, estimates that when you're 30 days past due and your balance is still unpaid, your score could take a 60-point hit. That kind of drop could mean a much higher interest rate on loans you take out (see table at right).

Late payments from your past that you have since paid off will have less and less of a negative effect on your score as time goes on. Johnson estimates that on average past delinquencies that have since been resolved might cost you 15 to 20 points.

To boost your score: Pay your bill in full and mail it as soon as it arrives, or at the very least the minimum due. Set up automatic online bill payments so you'll never be late. Or, if you are late one month, be sure to pay off what you owe as soon as possible.