Where and how to report suspected tax fraud

You can report suspected tax fraud to the IRS through three main channels: the online form on the IRS website, by mail, or by phone. The most direct route is Form 3949-A (Information Referral), which you submit to the IRS Criminal Investigation division. You can also use the IRS's online whistleblower portal at www.irs.gov/fraud, which accepts reports about individuals, businesses, or tax professionals who may be cheating on their taxes.

If you have evidence of fraud by a tax professional — a CPA, enrolled agent, or tax preparer — you can also report them to the Treasury Inspector General for Tax Administration (TIGTA) at www.tigta.gov. TIGTA investigates misconduct by people who work in the tax system itself, separate from investigations into individual taxpayers.

The IRS Criminal Investigation division handles the most serious cases: deliberate evasion, false returns, and identity theft used for tax purposes. If you believe you have witnessed criminal activity, not just an honest mistake or aggressive tax position, that distinction matters for where your report goes and how quickly it moves.

Key Takeaways

  • The IRS online whistleblower form at www.irs.gov/fraud is the fastest way to report suspected tax fraud by an individual or business.
  • Form 3949-A (Information Referral) can be mailed to the IRS Criminal Investigation division if you prefer to submit a written report with documentation.
  • Reports about tax professionals should go to TIGTA (Treasury Inspector General for Tax Administration) at www.tigta.gov, not the general IRS fraud line.
  • You do not need to prove fraud — you only need to describe what you observed and let the IRS decide whether to investigate.
  • The IRS keeps your identity confidential if you request it, though some information may be disclosed if the case goes to court.

What information the IRS needs from you

The IRS does not require you to have a complete case before you report. You can report based on suspicion, and investigators will decide whether to pursue it. However, the more specific your information, the more useful your report is. Gather what you can: the person's or business's name, address, and tax identification number (Social Security number or EIN); the years involved; and a description of what you observed that suggests fraud.

Concrete details matter more than conclusions. Instead of "I think they're hiding income," describe what you saw: "The business reported $50,000 in annual revenue but I saw daily cash sales receipts totaling $200,000 over a three-month period" or "The employee told me they were paid in cash and never received a W-2." If you have documents — bank statements, emails, receipts, or pay stubs — note what you have and where it is. You do not need to attach originals; the IRS will request them if they open an investigation.

If the fraud involves identity theft (someone using another person's Social Security number to file a false return), say that explicitly. Identity theft cases move through a different process and are treated as higher priority by both the IRS and law enforcement.

Using the IRS online whistleblower form

The IRS whistleblower portal at www.irs.gov/fraud is designed for reports about tax evasion by individuals and businesses. You fill out a form with the person's or entity's information and a description of the suspected fraud. The form asks whether you have direct knowledge of the fraud or whether you are reporting based on what someone else told you — answer honestly, because firsthand knowledge carries more weight in an investigation.

You will be asked whether you want to remain anonymous. If you choose anonymity, the IRS will not contact you for follow-up questions, but your report will still be reviewed. If you provide your contact information, an investigator may reach out if they need clarification. Either way, the IRS keeps your identity confidential from the person you are reporting, with limited exceptions if the case becomes a criminal prosecution and you are called as a witness.

After you submit the form, you will receive a confirmation number. The IRS does not provide status updates on individual reports, so keep that number if you want to reference your report later. There is no timeline for investigation — some reports are reviewed within weeks, others take months or longer depending on the IRS's workload and the complexity of the case.

Mailing Form 3949-A to the IRS

Form 3949-A is the official IRS form for reporting suspected tax fraud. You can read it from www.irs.gov or request it by phone. Fill out the form with the suspected violator's information and a detailed description of the fraud. Attach any supporting documents you have — copies only, not originals — and mail the form to the IRS Criminal Investigation division at the address listed on the form itself (the address varies by region).

The advantage of mailing Form 3949-A is that you create a paper record and can include attachments. The disadvantage is that mail takes longer and you have less certainty about when or whether your report is received. If you mail the form, consider using certified mail with return receipt so you have proof of delivery.

Do not mail original documents. The IRS will not return them, and you may need them for your own records or for law enforcement if a criminal case develops. Make copies, keep the originals, and send only the copies.

Reporting tax professionals and preparers

If the suspected fraud involves a tax professional — someone who prepared a false return, advised a client to claim false deductions, or helped hide income — report them to TIGTA at www.tigta.gov. TIGTA investigates misconduct by tax professionals, enrolled agents, CPAs, and tax preparation firms. You can also call TIGTA's hotline at 1-800-366-4484.

Describe what the professional did: Did they prepare a return they knew was false? Did they encourage a client to claim deductions they were not may have access to to? Did they fail to report income they knew about? TIGTA takes these reports seriously because tax professionals have a duty to follow the law and a conflict of interest when they benefit from helping clients evade taxes.

If the professional is also a CPA or enrolled agent, you can file a complaint with your state's accounting board or the IRS Office of Professional Responsibility. TIGTA will investigate the conduct; the state board or IRS may take disciplinary action like revoking their license or credentials.

What happens after you report

The IRS Criminal Investigation division receives thousands of reports each year and investigates only a fraction of them. Your report will be reviewed to determine whether it describes conduct that meets the threshold for investigation. Not every aggressive tax position or questionable deduction rises to the level of criminal fraud — the IRS distinguishes between tax avoidance (legal) and tax evasion (illegal).

If the IRS decides to investigate, you will not necessarily be told. Investigations are confidential, and the IRS does not provide updates to the person who reported the fraud. You may learn about the outcome only if the case becomes public — for example, if criminal charges are filed or if there is a settlement announced.

In rare cases, if the IRS recovers money as a result of your report and the case involves a substantial amount, you may be may be able to access for a whistleblower award under the IRS Whistleblower Program. Awards range from 15 to 30 percent of the recovery, but only if the recovery exceeds $2 million. You do not explore for an award when you report; the IRS determines may be able to access after the case is resolved.

The difference between fraud and mistakes

Tax fraud requires intent — the person knowingly filed a false return or deliberately hid income. A mistake, even a large one, is not fraud. If someone miscalculated their deductions or forgot to report a small amount of income, that is an error the IRS can correct through an audit, but it is not criminal fraud.

The distinction matters because the IRS has limited resources and prioritizes cases with clear evidence of deliberate wrongdoing. If you are reporting someone because you suspect they made an honest mistake, say that in your report. If you are reporting because you believe they intentionally deceived the IRS, describe the evidence that shows intent: Did they hide records? Did they use multiple identities? Did they deliberately underreport income they knew about?

Intent is hard to prove from the outside, and the IRS knows that. You do not need to prove intent yourself — describe what you observed, and let investigators decide whether it shows deliberate fraud or carelessness.

Frequently Asked Questions

Can I report someone anonymously?

Yes. The IRS online whistleblower form and Form 3949-A both allow you to submit a report without providing your name or contact information. If you choose anonymity, the IRS will not contact you for follow-up questions, but your report will still be reviewed and investigated if it meets the threshold for investigation.

What if I'm not sure whether what I saw is actually fraud?

Report it anyway. You do not need to be certain or to have proof. Describe what you observed — the facts, not your conclusions — and let the IRS decide whether it warrants investigation. Investigators are trained to distinguish between aggressive tax positions and illegal evasion.

Will the person I report know it was me?

Not unless you tell them or unless the case becomes a criminal prosecution and you are called as a witness. The IRS keeps your identity confidential from the person being investigated. If the case goes to trial, you may be subpoenaed to testify, but that is rare and happens only in serious cases.

How long does it take for the IRS to investigate?

There is no set timeline. Some reports are reviewed within weeks; others take months or longer. The IRS Criminal Investigation division has limited staff and prioritizes cases involving large amounts of money or organized fraud schemes. You will not receive status updates on your report.

Can I get a reward for reporting tax fraud?

Only if the IRS recovers more than $2 million as a result of your report and the case involves a substantial tax issue. Awards range from 15 to 30 percent of the recovery. You do not explore for an award when you report; the IRS determines may be able to access after the case is resolved and contacts you if you may have access to.