It is important to report fraud to the major credit bureaus (Transunion, Experian, and Equifax), because fraudulent accounts can harm your credit score and impair your ability to open new accounts. Notify all three bureaus in writing, and ask them to place a fraud alert on your credit reports so no more fraudulent accounts can be opened (see Resources section). Also ask them for copies of your credit reports so you can review them for any incorrect information related to the fraud. You are entitled to free copies of your reports as a fraud victim, and you can file disputes on any erroneous information so the bureaus can remove it.
You will strengthen your case if you are able to provide documentation. Contact the police as soon as you discover that you're a fraud victim and fill out police reports. Get copies of these reports so you can provide them to the credit bureaus when you contact them to report the fraud. Keep copies of any correspondence you have with credit card issuers and any other businesses involved in the fraud.
Monitor your reports from the three credit bureaus to make sure that no additional fraudulent accounts show up. Request copies of your credit reports every month or two and go through them line by line. If you find any erroneous information, immediately report it to the credit bureaus and file a dispute so it can be removed.