If you're asking yourself this question because of the Target security breach, you should take immediate action.
Target is advising some 40 million customers who shopped at one of its stores between Black Friday and December 15 to change PINs on debit cards and check credit card statements for suspicious activity.
The Federal Trade Commission echoes that advice but offers further options for consumers affected by data breaches.
According to the FTC, you may also opt to place a fraud alert on your credit file and exercise your right to a free copy of your credit report.
For more advice from the FTC on protecting your identity, visit www.consumer.ftc.gov/features/feature-0014-identity-theft