Where and how to report suspected tax fraud

Tax fraud means someone deliberately lied on a tax return to pay less tax than they owe. You can report it to the IRS using Form 3949-A (Information Referral) or by filing a written complaint with the IRS Criminal Investigation division. The fastest route is the IRS website at www.irs.gov/fraud, where you can submit details online without creating an account. You can also mail a letter with the details to your local IRS office, or call the IRS at 1-800-829-0433 to ask where to send it in your area.

The IRS takes three types of reports: someone filing a false return in their own name, someone using a stolen identity to file, or a tax professional preparing fraudulent returns for clients. Each one goes to a different department, so being clear about what you witnessed matters. You do not need to be certain — suspicion is enough to file a report. The IRS will investigate if the tip has enough detail to follow.

Reports can be anonymous. You do not have to give your name, and the IRS will not contact you to ask follow-up questions if you do not provide contact information. However, if you are a whistleblower with direct knowledge of fraud and want to claim a reward, you must identify yourself and provide enough evidence that the IRS can use in court.

Key Takeaways

  • File Form 3949-A with the IRS, mail a letter to your local IRS office, or report online at www.irs.gov/fraud — all three routes reach the same Criminal Investigation unit.
  • Include the person's name, Social Security number or tax ID, the tax year in question, and specific details about what you saw or heard — vague reports are harder to investigate.
  • You can report anonymously, but whistleblowers who claim a reward must provide their name and enough evidence for the IRS to use in court.
  • The IRS Criminal Investigation division handles the report, not the regular audit office, and they decide whether to open a case based on the details you provide.
  • Rewards are available only if the IRS recovers more than $2 million from the case, and the amount is between 15 and 30 percent of what was recovered.

What information to include in your report

The more specific you are, the faster the IRS can act. Start with the person's full name, address, and Social Security number or Employer Identification Number (EIN) if you know it. If you do not have the Social Security number, a business name or phone number helps. Then describe what you witnessed: which tax year, what was false on the return, and how you know it was false.

Examples of useful details: "I worked for John Smith in 2022 and he paid me $40,000 in cash but reported only $10,000 on his business return" or "My neighbor claimed three children as dependents on her 2023 return, but I know she has no children and was claiming her sister's kids." If you have documents — a pay stub, a lease, a bank statement — mention that you have them. Do not send originals; the IRS will ask for copies if they need them.

If a tax professional prepared the fraudulent return, include their name, firm name, and address. The IRS has a separate unit for tax preparer fraud and will route your report there. If you do not know all these details, report what you do know. Incomplete reports still get investigated if they contain enough to start with.

Using Form 3949-A versus online reporting

Form 3949-A is the official IRS form for reporting fraud. You can read it from www.irs.gov, fill it out by hand or on your computer, and mail it to the IRS Criminal Investigation office in your state. The form has spaces for the suspect's information, the tax year, and a description of the suspected fraud. It is straightforward and leaves a paper trail.

Online reporting at www.irs.gov/fraud is faster and does not require printing or mailing. You fill out a web form with the same information and submit it when ready. The IRS prefers online reports because they are easier to enter into their system. Both methods reach the same investigators, so choose whichever is easier for you.

If you are reporting a stolen identity case — someone filed a return using your Social Security number or someone else's — the IRS has a separate online tool at www.irs.gov/identity-theft. Use that tool instead of the general fraud report, because identity theft cases go to a different team and move faster through their system.

Anonymous reporting and whistleblower rewards

You can file a report without giving your name. The IRS will not try to contact you, and your identity stays confidential. This is useful if you are worried about retaliation or do not want to be involved in an investigation. Anonymous reports are treated the same as named reports and go to the same investigators.

Whistleblower rewards are different. If you have direct knowledge of tax fraud and the IRS recovers money because of your report, you may be may have access to to a reward. The reward is between 15 and 30 percent of the amount recovered, but only if the IRS collects more than $2 million. You must file Form 211 (process for Award for Original Information) and provide your name, contact information, and detailed evidence. The IRS will not pay a reward on an anonymous tip.

Rewards take time. The IRS must investigate, prosecute if needed, and collect the money before calculating your reward. This can take several years. You also need to prove you were the original source of the information — if multiple people reported the same fraud, the IRS may split the reward or give it to whoever reported first.

What happens after you file a report

The IRS Criminal Investigation division receives your report and decides whether to open a case. They look at whether the fraud is large enough to warrant investigation, whether they have enough detail to start, and whether they have the resources available. Not every report becomes a case. Small frauds or reports with too little detail may be closed without investigation.

If they open a case, investigators will gather documents, interview people, and build evidence. This can take months or years. You will not hear updates unless you are a named whistleblower with a reward claim. Even then, the IRS does not share investigation details while the case is open.

Criminal prosecution is possible if the evidence is strong enough. The IRS can refer cases to the Department of Justice, and the person may face criminal charges, prison time, and fines. Civil penalties are also common — the IRS may assess back taxes, interest, and fraud penalties without filing criminal charges. You do not need to follow the case to completion; your job is to report what you know.

Reporting fraud by a tax professional or preparer

If a tax preparer, CPA, or enrolled agent prepared a fraudulent return for a client, report it to the IRS Criminal Investigation division using the same methods as any other fraud report. Include the preparer's name, business address, phone number, and the names of clients whose returns you believe were falsified.

You can also report tax preparer misconduct to the IRS Office of Professional Responsibility. This office handles complaints about CPAs, enrolled agents, and other tax professionals who violate ethics rules or the tax code. File Form 14157 (Complaint About a Tax Return Preparer) if the preparer made errors or charged unreasonable fees, or use the general fraud report if you believe they deliberately filed false returns.

Preparer fraud is taken seriously because it affects many clients at once. A single dishonest preparer might file dozens of fraudulent returns, so reporting one case can stop a larger scheme. The IRS may suspend or revoke the preparer's license to practice.

Reporting identity theft and stolen Social Security numbers

If someone filed a tax return using your Social Security number or someone else's, that is identity theft, not traditional tax fraud. Report it when ready at www.irs.gov/identity-theft using the IRS's dedicated tool. You will need your Social Security number, date of birth, and filing status. The IRS will flag your account and send you a PIN to use on future returns so only you can file.

Also file a report with the Federal Trade Commission at www.identitytheft.gov. The FTC maintains a record of identity theft complaints and can help you dispute fraudulent accounts with banks and credit card companies. Keep copies of both reports for your records.

If the fraudulent return was filed in a prior year, you may need to file an amended return (Form 1040-X) once the IRS resolves the identity theft case. The IRS will contact you with next steps. Do not ignore notices from the IRS about a return you did not file — that is usually the first sign that someone used your number.

Frequently Asked Questions

Do I need proof to report tax fraud, or is suspicion enough?

Suspicion is enough to file a report. You do not need to have documents or be 100 percent certain. The IRS will investigate if your report contains enough detail to start with. However, if you want to claim a whistleblower reward, you will need solid evidence that the IRS can use in court.

What if I report someone and they find out it was me?

You can file an anonymous report so the person never knows you reported them. If you file a named report and are worried about retaliation, tell the IRS Criminal Investigation office when you file. They take threats seriously and can advise you on next steps. You can also consult an attorney about your options.

Can I report tax fraud to my state instead of the IRS?

Yes. Most states have their own tax fraud hotlines or online reporting tools. State tax agencies investigate fraud on state returns. If the fraud involves both federal and state taxes, you can report to both. Contact your state's Department of Revenue or tax authority to find out how to report.

How long does it take for the IRS to investigate a fraud report?

There is no set timeline. Some cases are investigated within months; others take years. The IRS prioritizes cases based on the amount of money involved and the strength of the evidence. You will not receive updates unless you filed a named whistleblower claim with Form 211.

What if the person I am reporting is a family member?

You can still report it. The IRS does not care about your relationship to the person. If you are uncomfortable reporting a family member, you can file an anonymous report. However, if you are a dependent on their return or they claim you as a dependent, consult a tax professional first about how this might affect your own tax situation.