A CP2000 is not a bill. It is a proposal: the IRS compared income or payment information it received from third parties, such as employers and banks, with the client's return, found a mismatch, and proposes changes that could raise, lower or leave the tax unchanged. The response is due 30 days from the notice date, or 60 days if the client lives outside the United States. This article gives a workflow a tax team can run the day a notice arrives.
What is a CP2000 and what does it say?
The IRS describes the CP2000 as a notice that income or payment information from third parties "doesn't match what you reported on your tax return." The notice lists each item, the proposed change to income, and the resulting proposed tax, penalties and interest. It includes a response form and the address or fax number for the IRS location handling the case.
The notice is a proposal, not an assessment. The client can agree, disagree in whole or in part, or report that the notice is correct and that other items also need to be reported.
What is the deadline?
Per IRS Tax Topic 652, respond within 30 days of the notice date, or 60 days if the client lives outside the U.S. A notice dated November 2, 2026 therefore calls for a response by December 2, 2026. The notice itself shows the exact response date, and that date controls. Log it the day the notice reaches the firm.
If the response is not received by that date, the IRS sends a Statutory Notice of Deficiency. Under section 6213(a), the client then has 90 days from mailing (150 days if the notice is addressed to a person outside the United States) to petition the Tax Court, and the IRS generally cannot assess the deficiency until that period expires. Saturdays, Sundays and D.C. legal holidays do not count as the last day, and a petition filed by any later date specified in the notice is timely. The statutory notice is sent to the client's last known address under section 6212(b)(1), so keep address records current with the IRS.
Step 1: Intake and authority
- Record the notice date, the response date, the tax year and the notice number.
- Check for a power of attorney. If the firm is not on file, Form 2848 lets a tax professional act for the client.
- Rule out identity theft. The IRS provides Form 14039 for that purpose.
- Pull the as-filed return, the wage and income transcript and the third-party forms behind each line.
Step 2: Reconcile each flagged item
Treat every line of the notice as its own test. Common causes:
- Income reported on the wrong line. The amount is on the return but the IRS matched it to a different line.
- Basis not reported. The information return shows gross proceeds only, and the return reported the net gain.
- Duplicate or incorrect third-party form. An issuer error or a corrected form that was never sent.
- Income belonging to someone else, such as a nominee or a different taxpayer using the same number.
- True omission. The income was never reported.
Worked example. A client sold securities with proceeds of $18,000 shown on the information return, and the return reported a gain of $3,500 (proceeds less basis of $14,500). The notice proposes treating $18,000 as gain. Assume a 15 percent rate for illustration. The proposed tax on the item is 15% x $18,000 = $2,700. The correct tax on the item is 15% x $3,500 = $525. The response should show the sale, the basis records, and the reconciliation from $18,000 to $3,500. The difference of $2,175 is the amount in dispute, before interest and any penalty.
For the reconciliation techniques on payment-card and marketplace forms, see reconciling Form 1099-K to gross receipts. Reporting thresholds are covered in Form 1099 thresholds for 2026.
Step 3: Choose the response
The IRS gives three paths:
- Agree. Complete, sign and date the response form and return it by the date listed. Then pay the tax due or settle it. The IRS points clients who cannot pay in full to a payment plan or an offer in compromise.
- Disagree. Mark the disagree box on the response form, include a signed statement explaining why, and attach supporting documents. Send everything by the due date.
- Notice correct, other items to report. File Form 1040-X for the year shown on the notice, write "CP2000" at the top, and send it with the response form and supporting documents. The IRS says that if the client agrees and has no other income, credits or expenses to report, an amended return is not needed.
Responses can be uploaded through the IRS document upload tool, faxed to the number for the location shown on the notice, or mailed to the address in the top left corner of the first page. A partial agreement should state item by item what is agreed and what is disputed.
If the firm needs more time, ask for an extension before the response date passes and note the result in the file.
How do interest and penalties work?
The IRS page says interest accrues until the balance is paid and penalties may apply, and it gives no amounts. The notice itself and Notice 746 explain how interest and penalties are figured, so record the dates and amounts shown on the client's notice. If the notice proposes an accuracy-related penalty, test it against the rules in section 6662 and reasonable cause. For penalty relief on filing and payment penalties, see first time penalty abatement.
What goes in the file?
- The notice, envelope or delivery date, and the response date calendar entry.
- The transcript and the as-filed return.
- A one-page reconciliation per disputed item, tied to source documents.
- The signed response form and the proof of transmission (upload receipt, fax confirmation or certified mail receipt).
- Follow-up dates. Check for the IRS reply and note any new notice number.
- A prevention note for next season: which third-party forms the client should send before the return is prepared. See tax season workflow from intake to e-file.
For calls to the IRS about the case, use the practitioner priority service guide.
CORAA prepares ready-to-review audit files for US CPA firms; see /us.
Sources
- Internal Revenue Service, Understanding your CP2000 notice: https://www.irs.gov/individuals/understanding-your-cp2000-notice
- Internal Revenue Service, Topic no. 652, Notice of underreported income: https://www.irs.gov/taxtopics/tc652
- Cornell Law School Legal Information Institute, 26 U.S.C. 6213, Restrictions applicable to deficiencies; petition to Tax Court: https://www.law.cornell.edu/uscode/text/26/6213
- Cornell Law School Legal Information Institute, 26 U.S.C. 6212, Notice of deficiency: https://www.law.cornell.edu/uscode/text/26/6212
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AU-C references are to AICPA Professional Standards, paraphrased here; read the standard itself before relying on a requirement. This page is guidance, not professional advice. Report an error