The Internal Revenue Service allows citizens to anonymously report suspected tax fraud activity by filling out and mailing in the appropriate forms. The IRS does not accept reports of suspected tax fraud over the telephone. Citizens can call the IRS tax fraud hotline at 1-800-829-0433 to hear recorded reporting instructions.
CNN reports that while someone can report tax fraud anonymously to the IRS, those willing to name themselves may be entitled to an award if the information is used by the IRS to collect funds. According to CNN, an IRS informant can receive between 15 percent and 30 percent of the amount collected by the IRS if the amount totals at least $2 million or the individual taxpayer being investigated has an annual salary of over $200,000.