CP2000. Proposed change from an information return.

On the paper

Compare each income item and each proposed change against your return, your Forms W-2 and 1099, your basis records, and the rest of your source documents.

Read the payer name next to each disputed item. The mismatch is usually traceable to one payer, and the fix depends on which one: a brokerage that reported gross proceeds without basis, an employer that filed a corrected form, or a payer that used the wrong taxpayer identification number. The proposed tax figure is the last thing to look at, not the first.

Find the date printed on your notice or letter. The paper notice and the current official IRS instructions control, even where this page differs.

Where this notice comes from

The IRS matches the income reported on returns against the information returns payers file for the same year. CP2000 is the output of that matching program, and it usually arrives a year or more after the return was filed.

Because the notice is machine-generated from one side of the transaction, it often proposes tax on gross amounts that the return reported net. A brokerage sale is the classic case: the information return shows the proceeds and the return shows the gain, and the mismatch resolves once basis is supplied.

The response date matters beyond politeness. If the IRS does not hear from you, the next document is a statutory notice of deficiency, which starts the Tax Court clock and is the last step before the tax is assessed.

General next steps

1. Mark each item on the notice as correct, incorrect, or not yours.
2. If the proposal is right, use the response form to agree and follow the payment instructions.
3. If it is wrong, send the response form with a signed explanation and the records that prove the point, and keep proof of what you mailed and when.

Timing

IRS Tax Topic 652, checked September 10, 2026, states to respond within 30 days of the date of the notice, or 60 days if you live outside the United States, and that paying a proposed amount within 30 days stops additional interest and possibly additional penalties from accruing. The same topic states that if the IRS does not hear from you by the response date, it will send a statutory notice of deficiency. The date printed on the notice controls; do not calculate a deadline from this page.

What CP2000 does not mean

CP2000 is not a bill and not an audit. No tax has been assessed, and nothing has been decided. It also does not mean the IRS believes you underreported on purpose. The notice is generated from information returns, and the most common causes are a payer reporting the same income twice, a rollover reported as a distribution, and a securities sale reported without its cost basis.

What this page cannot tell you

This page cannot determine whether the proposed change is correct without the underlying return and the records behind each item.

IRS audit defense

This letter involves an IRS examination or a proposed tax adjustment. Read IRS audit defense.

IRS Appeals

This letter may offer review by the IRS Independent Office of Appeals. Read IRS Appeals.

Official sources

• Understanding your CP2000 series notice
• IRS Tax Topic 652, notice of underreported income CP2000

If anything on this page differs from your notice or from current IRS instructions, follow the notice and the IRS.

Common questions

• What happens if I do not respond to a CP2000?

  IRS Tax Topic 652 states that if the IRS does not hear from you by the response date on the notice, it will send a statutory notice of deficiency. That notice starts the period for filing a petition in the United States Tax Court.

• Do I need to file an amended return to answer a CP2000?

  Not usually. The notice includes a response form, and the IRS asks for that form plus an explanation and records. An amended return can complicate the matching file if it is sent instead of the response form.

• The notice taxes the full sale price of stock I sold at a loss.

  That is the most common CP2000 mismatch. The broker reported gross proceeds and the return reported the gain or loss. Sending the basis records for the sale is the response the notice is asking for.

• Does paying the proposed amount end it?

  Paying within 30 days stops additional interest, and possibly additional penalties, from accruing on the amount paid. It also signals agreement with the proposal, so it is a decision to make after checking the items rather than before.