What Is a CP2000 Notice?
A CP2000 is the IRS's way of saying: "The numbers on your return don't match what we received from your employer, bank, or broker." It's officially called a Notice of Underreported Income.
Here's the part most people don't know: a CP2000 is not a bill, and it's not an audit. It's a proposed change. You have the chance to agree, disagree, or partially agree before anything is final.
Why You Got One
The IRS runs an automated matching program that compares your tax return against every W-2, 1099, K-1, and 1099-B filed under your Social Security number. When something doesn't line up, a CP2000 goes out automatically — no human reviews it first. The most common causes:
- A forgotten 1099 — especially from a side gig, freelance client, or short-term platform work
- Stock or cryptocurrency sales where the IRS sees the total proceeds but not your cost basis, which can make the taxable gain look much larger than it is
- A late or corrected W-2 that came in after you filed
- Income accidentally reported under the wrong Social Security number
Good to know: because the IRS often doesn't have your full cost basis on investment or crypto sales, the proposed amount on a CP2000 is frequently overstated. Getting the real numbers in front of them can reduce what's actually owed — sometimes substantially.
What to Do Next
Read the notice carefully
Compare the IRS's numbers line-by-line against your own return and records.Pull your IRS transcripts
This confirms exactly what the IRS has on file — no guessing.Respond within 30 days
Agree, disagree, or partially agree — but don't stay silent. No response is treated as agreement.Challenge the penalty separately if needed
Even if you agree with the tax change, the accuracy penalty can often be disputed on its own.The Bottom Line
A CP2000 feels alarming because of who it's from, not usually because of what it says. Most get resolved with a clear response and the right documentation — no drama required.
Disclaimer: This page is provided for general educational purposes only and does not constitute tax or legal advice. IRS notice types, deadlines, and procedures described here are based on publicly available IRS guidance and are subject to change. Deadlines mentioned, including any 30-day or 90-day response windows, may not apply to your specific notice — always refer to the dates and instructions printed on your actual IRS notice. Consult a qualified tax professional before taking action. Reading this page does not create a client relationship with FL Tax Experts.