Section A: who you are reporting
Line 1 for an individual and line 2 for a business. The form says to leave blank any lines you do not know.
3949-A
Information Referral
- Agency
- IRS
- Revision
- Rev. 10-2020
- Fillable fields
- 74
- Pages
- 3
- Official source
- IRS form page
- Checked
- October 21, 2026
Form 3949-A: Information Referral
Form 3949-A, Information Referral, is the IRS form for reporting suspected tax law violations by a person, a business, or both. The About Form 3949-A page lists the kinds of violations it covers, such as false exemptions or deductions, kickbacks, unreported or unsubstantiated income, failure to file a return and illegal drug income.
The form asks for what you know about the person or business, the alleged violation, any unreported income by tax year, a short description of the facts and some optional details. Information about yourself is not required to process the report, and the form says it is never shared with the person or business you are reporting. Pages 2 and 3 hold the instructions.
The About page says reports can also be made through the Form 3949-A online experience. This page covers the October 2020 revision (Rev. 10-2020). You can fill out the PDF free in your browser on this page and download it without an account.
What's on Form 3949-A
Line 3: alleged violations
Sixteen check boxes, including false exemption, false deductions, multiple filings, unreported income, kickback, failure to file return, failure to pay tax and other.
Line 4: unreported income
Spaces to enter tax years and dollar amounts of unreported income, if known.
Line 5: comments
A brief description of the facts: who, what, where, when and how you learned about and obtained the information in the report.
Line 6: additional information
Whether books or records are available, whether you consider the taxpayer dangerous, and the banks or financial institutions the taxpayer uses.
Section C: information about yourself
Your name, phone number, best time to call and address. The form says this is not required to process your report.
How to fill out Form 3949-A
- 1
Check that it is the right form
Read the caution list in the instructions first. The form says there may be other more appropriate forms specific to your complaint.
- 2
Describe the person or business
Complete line 1, line 2 or both, with as much information as you know.
- 3
Check the violations
On line 3, check all that apply. The instructions define each one; for example, unreported income means cash or other untraceable payments, such as goods or services, that were not reported.
- 4
Add income and the facts
On line 4, enter tax years and dollar amounts if known, in the style the form shows (TY 2010- $10,000). On line 5, briefly describe the facts and attach another sheet if needed.
- 5
Answer the optional questions
Line 6 is optional. The form says not to send books or records now; the IRS will contact you if they are needed for an investigation.
- 6
Add your details if you choose
Section C is optional. The instructions say information about yourself may be helpful if the IRS needs additional information.
Why fill Form 3949-A on indox
You get the real form, filled in a browser tab, with nothing standing between you and the finished PDF.
- Fill the form right in your browser, no software to install
- Free to fill and free to download, with no account
- The official blank straight from the IRS, not a copy someone retyped
- Works on a phone, tablet or computer
Where to send it and what to expect
Mailing address
The form says to print and send the completed form to Internal Revenue Service, PO Box 3801, Ogden, UT 84409.
Online option
The About Form 3949-A page says alleged violations can also be reported through the Form 3949-A Information Referral online experience.
Books and records
Do not send them with the form. The form says the IRS will contact you if they are needed for an investigation.
Your identity
Section C says the IRS never shares your information with the person or business you are reporting.
Rewards
The instructions say to use Form 211, Application For Award For Original Information, to claim a reward, and to mail it to the address in its instructions.
Time to complete
The Paperwork Reduction Notice gives an estimated average time of 15 minutes.
Related forms
Who uses Form 3949-A?
The person making the report completes the form and sends it to the IRS. The person or business being reported does not fill it out.
Official sources and the blank
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Questions about Form 3949-A
Do I have to give my name on Form 3949-A?
No. The form says information about yourself is not required to process your report, but would be helpful if the IRS needs to contact you.
Will the person I report learn who I am?
Section C of the form says the IRS never shares this information with the person or business you are reporting.
Can I file Form 3949-A online?
The About Form 3949-A page says you can report alleged tax law violations by filling out Form 3949-A online.
Can I get a reward through Form 3949-A?
The instructions say to use Form 211, Application For Award For Original Information, to claim a reward.
Is Form 3949-A used for identity theft?
No. The instructions say to use Form 14039 if you suspect your identity was stolen.
Where is Form 3949-A mailed?
The form prints Internal Revenue Service, PO Box 3801, Ogden, UT 84409.