Gather the taxpayer’s name, address, phone number, and Social Security number or EIN if known
Collect details of the suspected fraud, including dates, amounts, and how the fraud was committed
Save supporting documents, records, emails, invoices, bank statements, or other evidence
Complete IRS Form 3949-A, Information Referral
Submit Form 3949-A by mail to the IRS address listed in the form instructions
If you are a whistleblower seeking a reward and the underpayment exceeds the required threshold, complete IRS Form 211
Submit Form 211 to the IRS Whistleblower Office by mail
If you are reporting a tax return preparer, include the preparer’s name, address, PTIN if known, and details of the misconduct
If there is immediate danger, identity theft, or a threat to safety, contact local law enforcement first
If you are a victim of identity theft, file IRS Form 14039, Identity Theft Affidavit
Keep copies of everything you submit
Follow up with the IRS only if needed and after allowing time for processing