Who sends it: The IRS, by mail, when income reported by banks, employers or others does not match your return.
What this notice is
The IRS compares your tax return with forms like W-2s, 1099s and 1099-Rs that employers, banks and others send it. When they do not match, it sends a CP2000 showing the difference and how it would change your tax. The IRS says the notice is not a bill, but you may need to respond.
Common causes: a 1099 that never made it onto the return, such as bank interest, a retirement withdrawal or a small side job, or a stock sale reported without what you paid for the stock, which makes the whole sale price look like income.
The deadline
The response date is printed on the notice, and the IRS asks you to reply by that date. It is often about 30 days from the notice date. If you need more time, call the number on the notice before that date.
If you do not reply, the IRS may send a Statutory Notice of Deficiency, a formal notice with its own deadlines, and then a bill.
What to check
- Which income item the IRS lists, and who reported it
- Whether you already reported it on your return, maybe on a different line
- Whether the amount is right. Payers make mistakes too.
- For stock or fund sales, whether what you paid was counted
- The proposed tax, plus any penalty and interest shown
What to do: how to respond
Do not file an amended return just to answer a CP2000. The IRS says to amend only if the notice is correct and you also have other income, credits or expenses to report.
- Find the response form that came with the notice.
- If you agree, check that box, sign, and send it back. Ways to pay are listed at irs.gov.
- If you disagree with all or part of it, check that box and include a signed statement saying why, with copies of papers that back you up, such as a corrected 1099 or a record of what you paid for stock.
- Send it the way the notice says: through the IRS Document Upload Tool described in the notice, by fax, or by mail to the address on the notice.
- Keep copies of everything and note the date you sent it.
How to tell a real one from a fake
The IRS starts contact by mail. A real CP2000 shows the notice number CP2000 in a corner of the page, your name and the tax year. You can look up any notice by its number at irs.gov. To check a phone number, use the one listed at irs.gov or call 1-800-829-1040, not a number from an unexpected email or text. The IRS does not demand payment by gift card, wire or crypto, and does not threaten arrest.
Who can help
A tax preparer can help, especially with stock sales or retirement withdrawals. Free help may be available through the IRS Tax Counseling for the Elderly program. If you are stuck, the Taxpayer Advocate Service is a free, independent office inside the IRS.
Have one in front of you?
Take a clear photo and text it to Uncle at +1 208 214 0093. He tells you in plain words what it says, what it wants from you, and anything that looks wrong. How to take a clear photo.
This page explains what this kind of letter usually means. Your letter is the final word on your dates and amounts. For a decision about taxes, health coverage or a legal matter, call the office that sent it, using the number on its official website, or ask a professional you trust.
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Written by the Textuncle team. Last updated October 3, 2026.
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