Fill out and mail IRS Form 3949-A to the tax fraud reporting center. If you do not want to use Form 3949-A or cannot access it, you can mail a letter instead. The letter should include the name and address of the suspected individual, their taxpayer identification number (Social Security number for an individual), a brief description of the events including the tax year(s) involved, and the approximate amount of unreported taxes. The mailing address is:
Internal Revenue Service Fresno, CA 93888
Call the tax evasion hot line set up by the IRS to make an anonymous tip. If you do not wish to mail Form 3949-A or a letter to the IRS and you are not interested in receiving a reward for reporting tax fraud, call the hot line at (866) 775-7474.
Check to see if you might be eligible for a whistleblower reward. If you provide substantive information about someone who has not paid her taxes that leads to the IRS prosecuting that individual, then you might be eligible to collect this reward. If the dispute leads to a collection exceeding $2 million, or $200,000 for individuals, you might be eligible for a reward of 15 percent to 30 percent of the amount collected. For smaller amounts, the IRS will pay 15 percent. Use IRS Form 211 to submit this information and mail it to the following address:
Internal Revenue Service Whistleblower Office SE: WO 1111 Constitution Ave., NW Washington, DC 20224