What should I do if I get a CP2000 notice from the IRS?

A CP2000 is not a bill or an audit — it's an automated notice saying the income reported on your return doesn't match what third parties (employers, brokers, banks) reported to the IRS, usually a missed 1099 or mismatched cost basis. Read it carefully, because the IRS's proposed change is often only partly right. If you agree, sign and return the response form and pay or set up a plan. If you disagree, respond by the deadline (typically 30 days) with a written explanation and supporting documents, such as a corrected 1099 or basis records showing the sale wasn't all profit. Do not ignore it: silence lets the proposed tax become final. Most CP2000s can be resolved by mail without a phone call. Keep copies of everything you send.