To verify an IRS letter, find the CP or LTR number printed in the upper-right corner of the first page and look it up at irs.gov/notices. If the number matches a real notice, the site returns a description that should line up with what you received. You can also sign in to your IRS online account to see whether the notice appears in your records, or call the IRS at 1-800-829-1040 and read the notice number to a representative. Any one of those three steps will usually tell you within a few minutes whether the letter is genuine.
Look Up the Notice Number on IRS.gov
Every legitimate IRS notice carries an identifier in the upper-right corner of the first page. It starts with either CP (Computer Paragraph) or LTR (Letter), followed by a number and sometimes a letter suffix. That code is the fastest way to check the letter.1Internal Revenue Service. Understanding Your IRS Notice or Letter
Go to irs.gov and open the “Understanding Your IRS Notice or Letter” page, then enter the number exactly as it appears. If the number is valid, the site returns a plain-language explanation of why that notice gets sent, what the IRS expects from you, and how long you have to respond. Compare that description to your physical letter. The reason for contact, the tax year mentioned, and the general layout should all match.
If the lookup tool doesn’t recognize the number, read it again carefully. Suffixes like “C” or numeric extensions are easy to miss and change the meaning. If it still returns nothing after a careful second look, treat the letter as suspicious.
Check Your IRS Online Account
Your IRS Individual Online Account holds digital copies of the notices the IRS has actually sent you, along with your balance by tax year and your payment history.2Internal Revenue Service. Online Account for Individuals If the letter in your hand claims you owe a specific amount for a specific year and your account shows a zero balance for that year, the letter is almost certainly fraudulent.
Setting up an account requires identity verification through ID.me and takes a few minutes the first time. Once you’re in, the account is the most direct way to confirm what the IRS has on file for you. That matters most for notices about balance changes or account adjustments, where you can see the agency’s real numbers next to whatever the letter is asserting.
Call the IRS to Confirm
If you don’t want to work through the website, or you want a person to look at your account, call the IRS individual assistance line at 1-800-829-1040. It’s open 7 a.m. to 7 p.m. local time.3Internal Revenue Service. Let Us Help You Have the letter in front of you. Give the representative the date on the notice and the CP or LTR number, and they can confirm whether that notice exists in IRS records for your account.
One caution: only call the number above, or a number printed on a notice you have already verified through another method. Scammers spoof caller ID, print their own phone numbers on fake letters, and leave voicemails demanding a callback. The IRS does not leave pre-recorded voicemails threatening arrest.4Internal Revenue Service. Tips to Help Taxpayers Recognize Tax Scams If you get a message like that, ignore its callback number and dial 1-800-829-1040 yourself.
Signs the Letter Is Fake
Some features tell you a letter is fraudulent without any lookup at all. Tone is the biggest one. A real IRS notice reads like the bureaucratic form letter it is. A scam letter reads like a threat, demanding immediate payment, warning of arrest or deportation, or claiming you can’t dispute the amount.5Internal Revenue Service. Recognize Tax Scams and Fraud
Payment method is the other giveaway. The IRS accepts Direct Pay, EFTPS, checks, money orders, and credit or debit cards through approved processors. It will never ask you to pay with gift cards, prepaid debit cards, wire transfers, or cryptocurrency.6Internal Revenue Service. Ways to Tell if the IRS Is Reaching Out or if It’s a Scammer Any letter directing you to buy gift cards and read the numbers over the phone is a scam.
Watch for QR codes. The IRS has flagged scam letters and emails that include QR codes leading to fake websites built to harvest personal information. If a code takes you to a page that doesn’t end in .gov, close it.7Internal Revenue Service. Dirty Dozen Tax Scams for 2026 – IRS Reminds Taxpayers to Watch Out for Dangerous Threats
What a Real IRS Envelope and Letter Look Like
IRS mail arrives through the U.S. Postal Service. The return address in the upper-left corner shows a complete agency address, and the envelope is pre-printed with “Official Business” and “Penalty for Private Use, $300,” which is the standard government penalty mail language required on outgoing IRS correspondence. Those phrases are machine-printed, never handwritten or added later.8Internal Revenue Service. 1.22.3 Addressing and Packaging
The letter inside carries the Department of the Treasury seal and a government return address. Federal law requires an IRS notice to describe the reason it was sent and to itemize any tax, interest, and penalties assessed.9Office of the Law Revision Counsel. 26 USC 7522 – Content of Tax Due, Deficiency, and Other Notices A real notice also explains your appeal rights and gives you a response window, usually 30 or 60 days from the date on the letter, though some notices carry a strict 90-day deadline.10Internal Revenue Service. Letters and Notices Offering an Appeal Opportunity
Don’t Sit on a Certified Letter
One category of IRS notice can’t wait while you verify at your own pace. A Statutory Notice of Deficiency, often called a 90-day letter, is sent by certified or registered mail and tells you the IRS has found a difference between what you reported and what it believes you owe.11Office of the Law Revision Counsel. 26 USC 6212 – Notice of Deficiency You have exactly 90 days from the mailing date to file a petition with the U.S. Tax Court if you want to challenge the amount without paying first. If your address is outside the United States, you get 150 days. Miss the deadline and you lose the right to contest in Tax Court.12Taxpayer Advocate Service. Filing a Petition with the United States Tax Court
If a certified letter from the IRS arrives, open it the day it arrives and verify it that same day.
One other category surprises people: identity verification letters like CP5071, 5071C, 4883C, and 5747C. They ask you to confirm your identity because the IRS flagged a return filed under your Social Security number. They look alarming and many people assume they’re fake, but they’re usually real. Follow the instructions on the letter and use the phone number printed on that specific notice, which is dedicated to identity verification.13Internal Revenue Service. Understanding Your CP5071 Series Notice
If You’ve Confirmed It’s Fake
Report the letter to the Treasury Inspector General for Tax Administration (TIGTA) by calling 1-800-366-4484. Give them the return address on the envelope, any phone numbers listed in the letter, and any dollar amounts demanded.14TIGTA. Submit a Complaint
For suspicious emails, text messages, or scanned copies of fake IRS letters, forward them to phishing@irs.gov with “IRS” in the subject line.15Internal Revenue Service. Report Fake IRS, Treasury or Tax-Related Emails and Messages Don’t pay anything, don’t call the number the letter provides, and don’t scan any QR codes it contains.