The most common complaint the Federal Trade Commission receives involves identity theft: when someone steals your financial or personal information and uses it to run up charges on your existing accounts or to open accounts in your name without your knowledge. There are several ways to lessen your chances of being victimized: Never give any account number or Social Security number to someone who calls or e-mails you directly; shred all your financial statements and those annoying credit card offers; call 888-5OPTOUT to have your name removed from the credit bureaus' marketing lists; never carry your Social Security card with you; and ask any business or organization that requests your Social Security number as proof of your identity to come up with another option. (The Social Security number is the holy grail for identity thieves.) If, however, you become one of their victims, criminal defense lawyer Paula Canny of Burlingame, California, has these suggestions for reclaiming your financial identity:

1. Contact one of the national credit bureaus—Equifax (800-525-6285), Experian (888-397-3742), or TransUnion (800-680-7289)—and ask that a fraud alert be put on your account; it will caution any company checking your credit report to verify information about new accounts with you directly. Request a free credit report, which will list every account (bogus and real) that's in your name. And find out how to extend your fraud alert, which typically stays on your record for three months to a year.

2. File a police report at your local precinct. Tell them that you need a formal document to help you clear up the theft that has already occurred.

3. Contact the creditor of each illegitimate account and keep records of the conversations. You will be asked to fill out an affidavit; the FTC has a standard form, available at www.consumer.gov/idtheft. Send the creditor your police report—which validates your claim so creditors take you seriously—and the affidavit, and be sure to request a return receipt at the post office.

4. After you file this information, the creditor must, upon your request, give you documents pertaining to your account. This includes the application for the account and all transaction records, which you'll need to prove the fraud. Once you convince the creditor that you were a victim of identity theft, the institution should remove the charges from your account and alert the credit bureaus that the charges are no longer in dispute.