An explanation letter to the IRS is a written response that identifies the notice or issue you’re addressing, states your position in a few short paragraphs, and attaches labeled documents that back up what you say. Get the header, the notice reference, the facts, and the signature right, and most inquiries close without escalation. Miss one of those pieces and the letter can sit in a processing queue for months or be returned unprocessed.
What the Letter Should Contain
The IRS handles millions of pieces of correspondence, and letters missing key identifiers get routed slowly or lost. Every explanation letter follows the same skeleton.
- Header block with your full legal name (and your spouse’s name on a joint return), your Social Security Number, ITIN, or EIN, current mailing address, daytime phone number, and the date.1Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
- A subject line referencing the specific notice and tax year, for example “Re: Notice CP2000, Tax Year 2024.” If you’re writing proactively about a return you’re filing, reference the form and line item instead.
- The recipient address printed on the IRS notice you received. Different notices are handled by different processing centers, and sending your response to the wrong one causes significant delays.2Internal Revenue Service. Understanding Your CP2000 Series Notice
- A plain salutation. “Dear Internal Revenue Service” is fine.
- A body of short paragraphs with clear breaks between distinct points. The first paragraph states the issue and your position. Later paragraphs give facts and point to attachments.
- A signature above your printed name. Both spouses sign on a joint return. An unsigned letter will be returned without being processed, which can push you past your response deadline.3Internal Revenue Service. Policy Statement P-3-5
- An enclosure list at the bottom. Label each attached document (“Exhibit A: 2024 Brokerage Statement,” “Exhibit B: Corrected Form 1099-DIV”) and list every enclosure.
Send copies of everything, never originals. Keep a complete duplicate of the signed letter and all exhibits for your file.
A Sample Letter
This template responds to a CP2000 notice about a dividend the IRS says you failed to report. The same skeleton works for most other notice responses.
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 and the Form 1099-DIV from ABC Brokerage 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 It So It Works
The opening paragraph should say what you’re responding to and what you’re asking for. Name the notice number, the tax year, and the line item or issue. Something direct: “This letter responds to your CP2000 notice dated May 10, 2026, regarding Line 2b of my 2024 Form 1040. I disagree with the proposed adjustment for the reasons explained below.”
Present facts in chronological order with dates. If you’re explaining a missing 1099-DIV, state which brokerage issued it, when you received it, and where on your return you reported the income. If you’re asking for penalty relief, describe when the event happened and when you were able to resume filing and paying.
Skip emotional language. The reviewer processes hundreds of letters and a factual explanation moves faster than a description of how stressful the situation was. Every document you cite should be labeled as an exhibit and called out in the body. Instead of “see enclosed bank statement,” write “the enclosed brokerage statement (Exhibit A) shows the $4,800 in dividends was deposited on March 15, 2024.” That lets the reviewer match your claims to evidence without hunting through the packet.
One boundary worth naming: if the reason you’re writing is that a W-2 or 1099 reports income you never earned, the IRS wants Form 14039 (Identity Theft Affidavit), not a letter alone.4Internal Revenue Service. When to File an Identity Theft Affidavit You can attach a short cover letter, but the affidavit is what flags your account. Similarly, if you’re correcting an error on a return you already filed, file Form 1040-X. Part II of that form is itself an explanation field, so a separate letter isn’t strictly required, though a detailed letter attached to the amended return helps when the situation is complicated.5Internal Revenue Service. Form 1040-X Amended U.S. Individual Income Tax Return
If You’re Asking for Penalty Relief
Many explanation letters ask the IRS to abate a failure-to-file or failure-to-pay penalty assessed under Internal Revenue Code Section 6651. The failure-to-file penalty runs 5 percent of unpaid tax per month up to 25 percent, and the failure-to-pay penalty runs 0.5 percent per month up to 25 percent.6Office of the Law Revision Counsel. 26 U.S.C. 6651 – Failure to File Tax Return or to Pay Tax For returns filed more than 60 days late, the minimum failure-to-file penalty is the lesser of $525 or the full amount of tax owed for returns due after December 31, 2025.7Internal Revenue Service. Failure to File Penalty There are two ways to get those penalties removed.
Reasonable Cause
The IRS defines reasonable cause as a situation where you exercised ordinary business care and prudence but were still unable to comply on time.8Internal Revenue Service. Internal Revenue Manual 20.1.1 – Introduction and Penalty Relief Circumstances that qualify include fires and natural disasters, inability to obtain records, death or serious illness of the taxpayer or an immediate family member, and system issues that prevented a 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” is not enough. Give the dates of hospitalization, explain that no one else had access to your financial 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 same period. If you were too ill to file but were running a business and paying other bills, that undercuts the claim. Consistency matters.
First-Time Abatement
If you’ve been compliant for the previous three years, you may qualify for the first-time abatement waiver without proving reasonable cause. The IRS grants this administrative relief when you filed all required returns for the three prior tax 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 calling the number on your notice. You don’t need to name the program or submit documents; the IRS reviews your account and decides eligibility. If you want a paper trail, send a written request or file Form 843 (Claim for Refund and Request for Abatement). The phone route is faster; the written route gives you documentation if the request is denied.
How to Send It
USPS Certified Mail with Return Receipt Requested is the safest paper option. Under federal law, certified mail registration serves as evidence of delivery, and the registration date is treated as the postmark date for meeting deadlines.11Office of the Law Revision Counsel. 26 U.S.C. 7502 – Timely Mailing Treated as Timely Filing and Paying Keep the green return receipt with your copy of the letter.
Certain private carriers also qualify under the timely-mailing rule, including 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) Standard ground shipping from these carriers does not qualify. The carrier’s proof of mailing serves the same role as a certified mail receipt.
For many notice types, the IRS Document Upload Tool lets you submit your response and exhibits electronically. 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. Select the correct notice number from the drop-down — picking the wrong one delays processing. The tool cannot be used to submit tax returns.13Internal Revenue Service. IRS Document Upload Tool
If your CP2000 notice came with a response form, complete and sign it, mark whether you agree or disagree, and attach your explanation letter and exhibits. 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 You Cannot Miss
Missing a response deadline turns a manageable situation into a serious one. These are the ones that matter most for someone writing an explanation letter.
- CP2000 notice: 30 days from the notice date, or 60 days if you live outside the United States. If you don’t respond, the IRS assesses the proposed changes automatically.14Internal Revenue Service. Topic No. 652, Notice of Underreported Income – CP2000
- Notice of Deficiency (CP3219N): 90 days from the notice date to file a petition with the U.S. Tax Court, or 150 days if you’re outside the country. This deadline is absolute. Filing a return does not extend it. Miss it and your only option is to pay and file for a refund.15Internal Revenue Service. Understanding Your CP3219N Notice
- Collection Due Process hearing: 30 days from a Final Notice of Intent to Levy (Letter LT-11 or L-1058). Request the hearing on Form 12153.16Internal Revenue Service. Collection Due Process (CDP) FAQs
The 90-day Notice of Deficiency deadline is the one that catches people. By the time it arrives you’ve usually already missed earlier notices. Treat every IRS notice as time-sensitive even when the 30 days feels generous.
What Happens After You Send It
IRS correspondence processing has run well behind in recent years. As of mid-2026, the agency was processing individual general correspondence received in December 2025, a backlog of roughly six months.17Internal Revenue Service. Processing Status for Tax Forms Returns under review can take 45 to 180 days depending on the number and type of issues.18Taxpayer Advocate Service. Where’s My Refund?
Silence for a few weeks is normal. Follow up in writing if the response deadline on your notice passes with no communication. Reference your original submission date and your certified mail tracking number or Document Upload Tool confirmation. A few sentences is enough.
While the IRS reviews your response, it generally will not escalate collection activity on the issue you addressed. If a collection notice arrives anyway for the same tax year and issue, call the number on it and reference your earlier submission. That’s when the certified mail receipt earns its keep.
You can authorize a tax professional to handle the correspondence for you. Form 2848 (Power of Attorney and Declaration of Representative) lets an enrolled agent, CPA, or attorney communicate with the IRS, sign documents, and advocate on your behalf.19Internal Revenue Service. Instructions for Form 2848, Power of Attorney and Declaration of Representative Form 8821 (Tax Information Authorization) is narrower: it lets someone see and receive your tax information but not represent you.20Internal Revenue Service. About Form 8821, Tax Information Authorization And if you’re facing economic hardship or the IRS has delayed resolution beyond 30 days, the Taxpayer Advocate Service offers free help.21Internal Revenue Service. Who May Use the Taxpayer Advocate Service?