An explanation letter to the IRS is a short written response that identifies the notice or issue you’re addressing, states your position in one or two sentences, walks through the relevant facts in date order, and attaches labeled supporting documents. Get the header identifiers right, mail it to the exact address on the notice, and keep proof of when you sent it. That’s most of the job.
The rest is knowing what belongs in the letter, what to leave out, and which deadline you’re working against.
What to Include
Every letter needs the same identifiers at the top so the IRS can route it to your file. Missing any of these can send your response into a slow queue or lose it entirely.
- Your full legal name (and your spouse’s name, for a joint return), current mailing address, and a daytime phone number.
- Your Social Security Number, ITIN, or EIN. Taxpayers with an Individual Taxpayer Identification Number use that in place of an SSN.1Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
- A subject line that names the notice and tax year, such as “Re: Notice CP2000, Tax Year 2024.” If you’re writing without a notice, reference the form and line item.
- The date of the letter.
- The recipient address exactly as printed on the notice. Different notices go to different processing centers, and sending your response to the wrong one causes real delays.2Internal Revenue Service. Understanding Your CP2000 Series Notice
- A short body, in paragraphs. First paragraph: what you’re responding to and what you want. Following paragraphs: the facts, in order, with references to your exhibits.
- Your signature above your printed name. Both spouses sign a joint-return letter. An unsigned letter is returned unprocessed, which can push you past your response deadline.3Internal Revenue Service. Policy Statement P-3-5
- An enclosure list at the bottom, with each attachment labeled as an exhibit (“Exhibit A: 2024 Form 1099-DIV from ABC Brokerage”).
Send copies of supporting documents. Never mail originals. Keep a full duplicate of the signed letter and everything you attached.
Sample Letter
The template below responds to a CP2000 notice about an alleged dividend discrepancy. Change the facts to fit your situation, but keep the shape.
John A. Smith
123 Main Street
Anytown, USA 12345
SSN: XXX-XX-1234
Phone: (555) 123-4567
Date: June 15, 2026
Internal Revenue Service
[Address from top left corner of your CP2000 notice]
Re: Notice CP2000, Tax Year 2024
Notice Date: May 10, 2026
Dear Internal Revenue Service:
I am writing in response to the CP2000 notice referenced above, which proposes an increase of $1,200 in tax based on an unreported Form 1099-DIV from ABC Brokerage showing $4,800 in ordinary dividends on Line 2b of my Form 1040.
The $4,800 in dividends was reported on my original return. The amount appears on Schedule B, Line 5, as part of a combined total of $7,350 from three brokerage accounts. I have enclosed my 2024 Schedule B (Exhibit B) and the Form 1099-DIV from ABC Brokerage (Exhibit A) to confirm that this income was included.
Based on the enclosed documentation, I respectfully request that the proposed adjustment be withdrawn. Please contact me at the number above if you need additional information.
Sincerely,
[Signature]
John A. Smith
Enclosures:
Exhibit A: Form 1099-DIV from ABC Brokerage, 2024
Exhibit B: Schedule B as filed, 2024
Writing the Explanation So It Works
Open by naming the notice, the tax year, and the specific line item or issue, then state whether you agree or disagree and what you’re asking for. A first sentence like “This letter responds to your CP2000 notice dated May 10, 2026, regarding Line 2b of my 2024 Form 1040, and I disagree with the proposed adjustment for the reasons below” tells the reviewer everything they need to place your file.
Then walk through the facts chronologically, with dates. Which broker issued the 1099. When you received it. Where the income appeared on your return. If you’re asking for penalty relief, describe when the event started, when it ended, and when you were able to file or pay.
Keep the tone factual. The person opening your letter reads hundreds of these, and emotional language doesn’t move the file forward. A direct explanation with dates and exhibits does.
Tie every claim to an exhibit. Instead of “see enclosed statement,” write “the enclosed brokerage statement (Exhibit A) shows the $4,800 in dividends deposited on March 15, 2024.” That way the reviewer isn’t hunting through your attachments to match a claim to evidence.
A note on scope. If your issue is that someone filed a fraudulent return in your name or reported income you never earned, the IRS wants Form 14039, the Identity Theft Affidavit, not a plain letter.4Internal Revenue Service. When to File an Identity Theft Affidavit And if you’re correcting your own filed return before the IRS has contacted you, use Form 1040-X, which has a Part II built for your explanation.5Internal Revenue Service. Form 1040-X Amended U.S. Individual Income Tax Return
Asking for Penalty Abatement
A large share of explanation letters are written to knock down a failure-to-file or failure-to-pay penalty. Those penalties, assessed under Internal Revenue Code Section 6651, run 5 percent of unpaid tax per month for failure to file and 0.5 percent per month for failure to pay, each capped at 25 percent.6Office of the Law Revision Counsel. 26 U.S.C. 6651 – Failure to File Tax Return or to Pay Tax For returns due after December 31, 2025 that are filed more than 60 days late, the minimum failure-to-file penalty is the lesser of $525 or the full tax owed.7Internal Revenue Service. Failure to File Penalty Two paths exist for getting them removed.
Reasonable Cause
The IRS defines reasonable cause as a situation where you exercised ordinary business care and prudence but still couldn’t comply.8Internal Revenue Service. Internal Revenue Manual 20.1.1 – Introduction and Penalty Relief Recognized categories include fires and natural disasters, inability to obtain records, death or serious illness of the taxpayer or an immediate family member, and system failures that prevented timely electronic filing or payment.9Internal Revenue Service. Penalty Relief for Reasonable Cause
Your letter has to connect the event to the missed deadline. “I was in the hospital” isn’t enough on its own. Give the dates of hospitalization, explain that no one else had access to your records, and show that you filed within a reasonable time after recovery. Attach medical records or a doctor’s note.
The IRS also looks at how you handled the rest of your affairs during the period. If you were too ill to file but were running a business and paying every other bill, that undercuts the claim. Consistency across the record matters.
First-Time Abatement
If you’ve been compliant for the three prior tax years, you may qualify for administrative relief without proving reasonable cause at all. The IRS grants first-time abatement when you filed all required returns for the previous three years and had no penalties during that period, or any prior penalty was removed for a reason other than first-time abatement.10Internal Revenue Service. Administrative Penalty Relief
You can request it by phone using the number on your notice, and you don’t need to invoke it by name or send documents. The IRS checks eligibility from your account. If you want a paper trail, send a written request or file Form 843, Claim for Refund and Request for Abatement.10Internal Revenue Service. Administrative Penalty Relief
How to Send It
Certified Mail
USPS Certified Mail with Return Receipt Requested is the standard. Under federal law, certified mail registration is evidence of delivery to the IRS, and the registration date counts as the postmark date for deadline purposes.11Office of the Law Revision Counsel. 26 U.S.C. 7502 – Timely Mailing Treated as Timely Filing and Paying Keep the green return receipt card with your file copy.
IRS-Approved Private Delivery Services
Only specific service levels from designated carriers qualify under the timely-mailing rule. Qualifying options include FedEx Priority Overnight, FedEx Standard Overnight, UPS Next Day Air, UPS 2nd Day Air, and DHL Express, among others.12Internal Revenue Service. Private Delivery Services (PDS) Ground shipping from these carriers does not qualify.
IRS Document Upload Tool
For many notices, you can upload your response and attachments through the IRS Document Upload Tool. You’ll need the notice or letter number, your name as it appears on the notice, and your SSN, ITIN, or EIN. The system confirms receipt.13Internal Revenue Service. IRS Document Upload Tool Select the correct notice number from the drop-down; the wrong selection causes processing delays. The tool doesn’t accept tax returns.
CP2000 Response Form
CP2000 notices come with a response form. Fill it out, indicate agreement or disagreement, attach your letter and exhibits, and mail everything to the address in the top left corner of the first page of the notice.2Internal Revenue Service. Understanding Your CP2000 Series Notice
Deadlines to Watch
- CP2000: 30 days from the notice date, 60 days if you live outside the United States. If you don’t respond, the IRS assesses the proposed changes.14Internal Revenue Service. Topic No. 652, Notice of Underreported Income – CP2000
- Notice of Deficiency (CP3219N): 90 days from the notice date to petition the U.S. Tax Court, 150 days if you’re outside the country. Filing a return does not extend this. Miss it, and your only remaining option is to pay and file for a refund.15Internal Revenue Service. Understanding Your CP3219N Notice
The 90-day deadline is the one that catches people, usually because earlier notices were ignored. Treat every IRS notice as time-sensitive.
After You Send It
IRS correspondence processing has been running well behind. As of mid-2026, the IRS was working through individual general correspondence received in December 2025, roughly a six-month backlog.16Internal Revenue Service. Processing Status for Tax Forms If your case involves a return under review, the IRS says that can take 45 to 180 days depending on the issues.17Taxpayer Advocate Service. Where’s My Refund?
Silence for a few weeks isn’t a problem. Silence past the response deadline on your notice is. Send a short follow-up referencing your original submission date and your certified mail tracking number or upload confirmation. A few sentences is enough.
If a collection notice arrives for the same tax year and issue while your response is pending, call the number on the collection notice and reference your earlier submission. That’s the moment your certified mail receipt earns its keep.