Principales conclusiones
- Form 3949-A is the IRS’s official way for people to report suspected tax fraud or other tax violations. You can use it to report both individuals and businesses if you believe they're doing something shady with their taxes.
- You’re allowed to submit Form 3949-A anonymously, which means you don’t have to include your name or contact information unless you want to. The IRS will still take your tip seriously.
- The kinds of things you can report include unreported income, claiming false deductions, having hidden offshore accounts, or using someone else’s Social Security number.
- Form 3949-A can’t be submitted online. You have to print it out, fill it in by hand, and mail it to the IRS at the address provided in the form’s instructions. As of 2025, the main address is in Fresno, California.
- Submitting Form 3949-A does not mean you’ll get any kind of follow-up or reward. If you want to apply for a whistleblower payout, you’ll need to file Form 211 instead, which is a whole different process.
If you’ve ever come across someone who might be playing fast and loose with their taxes, you might have wondered whether there’s anything you can actually do about it. As it turns out, there is—and it’s called Form 3949-A.
Form 3949-A gives you a way to report suspected tax fraud or tax law violations confidentially. Whether you stumbled upon something suspicious at work, heard about some shady business practices, or have firsthand knowledge of someone underreporting their income, this form is one way the IRS collects leads for potential investigations.
Let’s walk through what Form 3949-A is all about, who should use it, how the process works, and what you should (and shouldn’t) expect after submitting it. We’ll cover everything from how to fill it out to what kinds of issues it’s meant for, so you know what you’re getting into.
What Is Form 3949-A?
Form 3949-A is the official IRS document for reporting suspected tax fraud or abuse. It’s formally called the Information Referral form. When you believe someone is violating tax laws—like not reporting income, claiming false deductions, or running a fake business—you can use this form to alert the IRS anonymously.
You don’t need to be an expert or prove anything beyond a reasonable doubt. The IRS uses the information you provide as a lead, and from there, they decide whether to investigate further.
You’re not required to attach evidence, although providing as much specific detail as possible definitely helps. The more accurate and complete your report, the more likely it is to be taken seriously and routed for review.
Common Reasons People Use Form 3949-A
Form 3949-A can be used in a variety of situations. Some of the most common include someone not reporting cash income, a person claiming dependents they shouldn’t be, or a business underreporting revenue while still issuing shady payments.
People also use the form when they suspect someone is using a fake Social Security number, failing to file tax returns, or hiding income offshore. If it sounds like tax evasion, and you have reason to believe it’s happening, this form is one of your reporting options.
While it’s often used by people with insider knowledge, like employees, business partners, or family members, you don’t need a direct connection. The IRS accepts tips from anyone who has credible information to share.
Who Should File Form 3949-A?
You might want to file Form 3949-A if you’ve observed or discovered what you believe is a violation of tax law. Maybe a contractor is getting paid in cash but not reporting it, or a landlord is collecting rent under the table.
Maybe you’ve seen someone claim a business that doesn’t actually exist just to get deductions. If you have real, specific details, not just vague suspicions, then submitting the form can help bring it to the IRS’s attention.
You don’t need to be a tax professional, and you don’t have to reveal your identity if you don’t want to. In fact, the IRS doesn’t require you to include your personal information at all. If you do provide your name, it may help in case they need clarification, but it’s not required and the IRS keeps it confidential.
How to Fill Out Form 3949-A
Form 3949-A is pretty straightforward. It asks for details like the name and address of the person or business you’re reporting, their Social Security Number or EIN if you have it, a description of what they did wrong, and how you know about it. You’ll also be asked for the tax years involved and the estimated dollar amounts, if you have any idea.
If you choose to include your own contact information, there’s a space for that. Otherwise, you can leave it blank and still submit the form. Once it’s filled out, you’ll need to mail it (there’s no option to file it online) to the IRS address listed in the instructions.
What Happens After You Submit the Form?
After you send in Form 3949-A, the IRS takes over. But here’s the thing: they won’t update you on what happens next. They can’t, for confidentiality reasons. That means you won’t get any confirmation or results—even if you provided your contact information. The IRS will review the form, compare it with other information they have, and decide whether or not to open an investigation.
If your information helps lead to the collection of unpaid taxes, and you’re interested in a potential reward, there’s a separate process for that involving Form 211 (that’s the one you’d use to apply for a whistleblower award). Just keep in mind that Form 3949-A alone won’t qualify you for any financial reward—it’s more of a civic tip-off tool.
What You Shouldn’t Use Form 3949-A For
Form 3949-A is a powerful tool for reporting suspected tax law violations, but there are specific situations where it is not appropriate to use this form. Below are some common scenarios where Form 3949-A would not be the right choice:
1. Reporting Identity Theft
If you believe your identity has been stolen, Form 3949-A is not the correct form to use. Instead, you should file Form 14039, Identity Theft Affidavit, which is specifically designed to address issues related to identity theft.
Form 14039 helps you report incidents where someone has fraudulently used your personal information to file a tax return or engage in other financial crimes. This form initiates the process to secure your tax account and helps the IRS take action to prevent further misuse of your information.
2. Suspicious IRS Communications (Phishing or Scam Calls/Emails)
If you’ve received a suspicious phone call or email claiming to be from the IRS, it’s important not to use Form 3949-A. These types of fraudulent communications, often referred to as phishing, are attempts by scammers to steal your personal information or money.
The IRS has a dedicated reporting system for phishing attempts and scams. You can report these incidents directly to the IRS through their phishing email reporting system or by calling the IRS fraud unit. The IRS keeps a close eye on phishing schemes to protect taxpayers and track down the criminals behind them.
3. Personal Disputes (e.g., Divorce or Custody Issues)
Form 3949-A is not meant to resolve personal disputes or grievances, such as those related to divorce or custody issues. For instance, if you’re in a messy divorce and suspect that your ex-spouse is incorrectly reporting income, claiming false deductions, or underreporting their earnings on their tax return, Form 3949-A is not the right tool.
This form is designed specifically for reporting tax law violations, and your personal disputes, even if they involve potential tax issues, should be resolved through the appropriate legal channels or family law attorneys. The IRS does not intervene in personal matters unless they are directly related to violations of tax law.
4. Inaccurate or Erroneous Tax Returns (Non-Violations)
If you suspect someone’s tax return is simply incorrect or has errors, but you don’t believe there is a violation of tax law (e.g., intentional underreporting of income or fraud), Form 3949-A is not the right vehicle.
While the IRS does handle mistakes on tax returns, the correct process for getting someone’s tax return corrected typically involves direct communication with the IRS through the amendment process or working with a tax professional. If you believe someone’s tax return is wrong but not fraudulent, you may need to contact the IRS in a different way or encourage the taxpayer to amend their return themselves.
Final Thoughts on Form 3949-A
Form 3949-A gives you a structured way to report suspected tax violations without needing to get personally involved. It’s a tool that helps the IRS find leads in their enforcement efforts, especially when dealing with under-the-table income or tax schemes that aren’t obvious on the surface.
Filing the form is pretty low-risk on your end, especially since it can be submitted anonymously. Just be sure you’re using it for the right reasons and with accurate information. The IRS takes every tip seriously, but they’re also selective about what they investigate, so the more precise your report, the more helpful it’ll be.
If you’re thinking about filing Form 3949-A, it’s a good idea to gather all your facts, be as specific as you can, and understand that the process is entirely confidential and one-way. You’re doing your part to help keep the tax system honest—no small thing in a world where everyone is supposed to pay their fair share.
Form 3949-A: FAQ
1. What exactly is Form 3949-A used for?
Form 3949-A is used to report tax fraud or violations of tax law. That can include things like someone not reporting income, exaggerating deductions, using a fake Social Security number, or running a business that doesn’t pay taxes properly. Basically, if someone is doing something they shouldn’t be doing with their taxes, and you know about it, this form lets you report it to the IRS confidentially. It’s a way for everyday people to flag suspicious tax behavior without having to prove anything beyond sharing what they know.
2. Can I remain anonymous when I file Form 3949-A?
Yes, you can absolutely remain anonymous. The IRS does not require you to give your name, phone number, or any personal contact information. There is a section on the form for that information in case you choose to provide it, but it’s totally optional. Even if you do give your name, the IRS keeps it strictly confidential and will not tell the person you’re reporting. Keep in mind, though, that if you stay anonymous, the IRS won’t be able to contact you if they need more information.
3. What happens after I send in the form?
Once the IRS receives your Form 3949-A, they review the information and compare it against other data they already have. If your report seems credible and worth pursuing, they may open an investigation. That said, the IRS will never follow up with you or let you know what happened. Because of privacy laws, they won’t confirm whether they looked into the issue, took action, or ignored it. So don’t expect any updates or feedback—it’s a one-way submission. You just have to trust that if the information is useful, they’ll take it from there.
4. What should I include in the report to make it more helpful?
The more specific your details are, the better. Include things like the name and address of the person or business, their Social Security Number or Employer Identification Number if you know it, the type of violation you believe occurred, and the years it relates to. You should also describe how you know about the violation—whether you saw documents, heard them talk about it, or witnessed something firsthand. If you can estimate dollar amounts or know exact figures, that helps too. The goal is to paint a clear enough picture that the IRS knows what to look for.
5. Is there anything I shouldn’t use this form for?
Yes, there are definitely situations where Form 3949-A isn’t the right tool. If you’re dealing with identity theft, you need to use Form 14039 instead. If you received a phishing email or scam phone call claiming to be from the IRS, that should be reported separately through the IRS’s phishing reporting system. And if you’re in a personal dispute—like a divorce or custody battle—and taxes are involved, Form 3949-A isn’t the place to work that out. It’s meant specifically for suspected tax violations backed by some level of fact or observation.
6. Can I submit supporting documents with Form 3949-A?
Yes, you can attach documents to support your claim if you have them. Things like invoices, emails, bank statements, or contracts can be helpful, especially if they clearly show something suspicious. Just make sure not to send original documents, because you won’t get them back. Always send copies and include them with the form in the envelope you mail to the IRS. While evidence isn’t required, it definitely strengthens your report and gives the IRS more to go on when deciding whether to investigate.
Jacob Dayan
Entrepreneur • CEO Community Tax, LLC
Jacob Dayan is the CEO and co-founder of Community Tax LLC, a leading tax resolution company known for its exceptional customer service and industry recognition. With a Bachelor’s degree in Business Administration from the University of Michigan’s Ross School of Business, Jacob began his career as a financial analyst and trader at Bear Stearns and Millennium Partners before transitioning to entrepreneurship. Since 2010, he has led Community Tax, assembling a team of skilled attorneys, CPAs, and enrolled agents to assist individuals and businesses with tax resolution, preparation, bookkeeping, and accounting. A licensed attorney in Illinois and Magna Cum Laude graduate of Mitchell Hamline School of Law, Jacob is dedicated to helping clients navigate complex financial and legal challenges.
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