Both numbers are real, and both come from Notice CP59, the IRS letter that says it has no record of your tax return for a given year. 855-800-8106 is a fax line for sending Form 15103 if you believe you didn’t have to file. 800-829-8374 is the phone number the notice gives for questions.
Updated September 25, 2026 · Checked against real notices our clients received
IRS notice number lookup
855-800-8106and 800-829-8374
IRS fax line and IRS phone line
- 855-800-8106
- IRS fax number for Form 15103, Form 1040 Return Delinquency.
- 800-829-8374
- IRS phone number for questions. The notice says: “If you can’t find what you need online, call us at 800-829-8374.”
- Printed on
- Notice CP59, “You need to file your [year] Form 1040 tax return.” We reviewed a version dated May 27, 2024.
- What CP59 means
- The IRS has no record of your return for the year listed.
- Cost
- Both are toll-free.
Which number do you need?
| Your situation | What to do |
|---|---|
| You needed to file and didn’t | File the return. The notice gives two options: file electronically through an authorized e-file provider, or mail the signed return with payment for any tax due. |
| You weren’t required to file | Complete Form 15103, then mail it or fax it to 855-800-8106. |
| You already filed | Say so on Form 15103 and include a signed and dated copy of the return you filed. |
| You have questions | Call 800-829-8374. The notice asks you to have your account information ready when you call. |
What the IRS says happens if you don’t respond
The CP59 we reviewed lists three consequences:
- “You may lose your claim to a refund or certain credits.” The tax code sets strict time limits for claiming them.
- “We may determine your tax for you.” Penalties and interest can keep building on whatever the IRS decides you owe.
- “You may become subject to backup withholding” on interest and dividends, meaning the IRS tells your bank or broker to hold back part of what it pays you.
Faxing Form 15103 to 855-800-8106
- Get Form 15103 at IRS.gov/F15103. The notice points you there.
- Check the box that fits your situation, then sign and date the form.
- Include the stub from the notice, or a copy of the notice, so the IRS can match the form to your account.
- Fax it with a regular fax machine or an online fax service. The notice asks you to understand your fax service’s privacy and security policies before you send.
- Keep the fax confirmation and a copy of everything you sent.
Don’t fax your whole tax return here unless your notice says to. The CP59 we reviewed lists this fax number for Form 15103, and tells you to file the return itself electronically or by mail.
If you owe but can’t pay, file anyway
The penalty for filing late is much bigger than the penalty for paying late. Under Internal Revenue Code section 6651, the failure-to-file penalty is 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. The failure-to-pay penalty is 0.5% a month. Filing now stops the bigger penalty from growing, and then you can set up a payment plan.
Calling 800-829-8374
The notice doesn’t print hours. The IRS’s main line for individuals runs 7 a.m. to 7 p.m. local time on weekdays, and the IRS says waits are longer on Mondays and Tuesdays. Have the notice, your Social Security number and your prior-year return in front of you.
Expect a wait on any IRS line tied to money you may owe. Here’s what the National Taxpayer Advocate reported for the 2026 filing season, through April 18, 2026.
Source: IRS, IR-2026-79, National Taxpayer Advocate mid-year report to Congress (June 24, 2026).
Behind on filing?
Let us handle the CP59 for you
We can call the IRS for you, pull your wage and income records, and prepare the missing return, or file Form 15103 if you truly didn’t have to file. See our unfiled tax return service.
CP59 phone and fax number FAQs
Is 855-800-8106 a phone number?
No. It's the fax number printed on Notice CP59 for sending Form 15103, Form 1040 Return Delinquency. To talk to someone about a CP59, the notice gives 800-829-8374.
What is Form 15103?
Form 15103, Form 1040 Return Delinquency, is how you tell the IRS why it doesn't have your return, for example because you weren't required to file or you already filed. The CP59 lets you mail it or fax it to 855-800-8106.
Can I fax my tax return to 855-800-8106?
The CP59 we reviewed lists that fax number for Form 15103 and tells you to file the return itself electronically or by mail. If you already filed, send a signed copy of that return along with Form 15103.
What are the hours for 800-829-8374?
The notice doesn't list hours. The IRS's main individual line is open 7 a.m. to 7 p.m. local time, Monday through Friday, and the IRS says waits are longer on Mondays and Tuesdays.
What happens if I ignore a CP59?
The IRS may figure your tax for you, penalties and interest can build, you can lose refunds and credits, and you may become subject to backup withholding on interest and dividends.
“They were friendly, professional, and encouraging. They helped straighten out my challenging tax situation and stuck with it until everything was resolved. I highly recommend!”
Other numbers from IRS and state tax notices
Sources
- Redacted Notice CP59 received by one of our clients (PDF), dated May 27, 2024.
- Our guide to IRS Notice CP59.
- 26 U.S. Code § 6651, Failure to file tax return or to pay tax.
- IRS, Telephone assistance.
- IRS, IR-2026-79 (National Taxpayer Advocate mid-year report).
Choice Tax Relief is a private tax resolution firm. We are not the IRS, the U.S. Treasury, or any government agency, and we are not affiliated with any private collection agency. You can call the IRS yourself at no charge. This page is general information, not legal or tax advice for your situation.