For more information, see Reporting Social Security fraud.
If you suspect or know of an individual or company that is not complying with tax law, you may report this activity by completing IRS Form 3949-A. You may fill out Form 3949-A online, print it and mail it to:
If you do not wish to use Form 3949-A, you may send a letter to the address above. Please include the following information, if available:
Although you are not required to identify yourself, it is helpful to do so. Your identity can be kept confidential.
For more information, see How Do You Report Suspected Tax Fraud Activity?
If you suspect someone of being an illegal alien who snuck into our country and evaded apprehension at our border, you can quickly and easily file a report to government agencies at the (non-government) website www.ReportIllegals.com. Depending on the data you provide, ReportIllegals.com will in most cases file a report to ICE and in many cases to federal agencies such as CIS, CBP, DOL, DEA, DSS, FBI, HUD, IRS, SSA, TSA, or other foreign, federal, state, county and local governmental agencies.
To report suspected illegal aliens directly, contact:
Contact the US Citizenship and Immigration Services (CIS, formerly INS), under the Dept of Homeland Security.
You can call the CIS National Service Center at 1-800-375-5283 to find your local office to report illegal aliens. Note that the default language of this U.S. government office is some foreign language - not English! Press 1 to speak in English, the native language of the United States of America. Then press 9 to speak to a real person. They should be able to help find a local office to take the report.
Also, see the article: "How To Report Illegal Aliens - Updated DHS Version!"