Reviewed and updated October 16, 2026
Rules and decisions to review
- Read the notice’s tax year, proposed changes and response deadline; keep every page.
- Compare the notice with the filed return and the payer’s information. Missing stock basis or duplicate reporting can make an apparent mismatch misleading.
- If you disagree, provide a clear explanation and supporting records through the response method specified on the notice.
- If you agree, follow the notice’s instructions for responding and paying. Do not automatically file an amended return as a substitute for the requested response.
A practical example
A broker reports gross stock-sale proceeds but the IRS does not have the purchase cost. The proposed increase may overstate taxable gain until the basis and transaction records are provided.
Records to gather
Gather the complete notice, filed return, matching Forms W-2 or 1099, basis records and any payer corrections.
Your next step
Send the complete CP2000 notice and supporting documents for review promptly. Calendar the response date, distinguish agreed from disputed items and retain proof that the response reached the specified destination.
Official sources
This guide provides general information. The rules depend on the tax year, jurisdiction and your circumstances. Ask our team which filing or planning steps apply to you.
