If you and your spouse use a singlecredit card that's in your name, yourspouse isn't creating a credit history, evenif their name is also on the card. The debtis yours and only your credit history isbuilt up as you use the card and pay offpurchases. A solid credit history is importantbecause it affects how much youpay on a variety of loans, from mortgagesto car loans. It can even determinehow much you get charged for car insurance.That means building up yourspouse's credit rating can be crucial. Getting a card in each spouse's name andswitching from 1 to the other can createa credit history for both of you.