CP-2000 Notice: What It Means and What to Do in the First 30 Days
8 min read · By Jonathan C. Do, Esq. · Updated for 2026
If you opened your mailbox to find an IRS CP-2000 notice, take a breath. Despite the official tone and the dollar figure printed at the top, a CP-2000 is not a bill — at least not yet. It's a proposal. And how you respond in the first 30 days will largely determine what happens next.
What a CP-2000 actually is
A CP-2000 is the IRS's Automated Underreporter notice. Their computer matched the income reported on your tax return against W-2s, 1099s, and other information returns sent by employers, banks, brokerages, and payment processors — and it found a mismatch.
The CP-2000 explains what the IRS believes you should have reported, calculates the additional tax (plus interest and a potential 20% accuracy-related penalty), and asks you to either agree, disagree, or partially agree.
Why you might have received one
The most common triggers are also the most innocent:
- A 1099 you forgot about (consulting income, brokerage gains, gambling winnings)
- A 1099-K from a payment processor (Stripe, PayPal, Square) that doesn't match your gross receipts
- A K-1 from a partnership or S-corp that arrived after you filed
- Brokerage cost-basis reporting that the IRS interpreted as a $0 basis (very common)
- A 1099-NEC reported by a payer who used the wrong year
In our practice, the most common CP-2000 we see is a brokerage 1099-B where the IRS treated short-term trades as if they had zero basis. The "underreported" income is a phantom — but the burden is on you to prove it.
The 30-day window: what to do
1. Find the deadline. Mark it everywhere.
The CP-2000 has a respond by date — usually 30 days from the notice date. Miss it and the IRS will issue a Notice of Deficiency (a "90-day letter"), which is a much harder document to respond to. The 30-day date is on page 1, upper right. Put it on your calendar, your phone, your fridge.
2. Read the notice carefully — twice.
Page 1 is the summary. Pages 2-5 list every item the IRS believes you underreported, with the payer, the document type, and the dollar amount. Compare each line to your tax return. Note any items you don't recognize.
3. Pull your supporting documents.
For each disputed item: gather the original 1099, brokerage statements showing your basis, K-1s, or any other proof of what you actually owed. For brokerage trades, you'll need the cost basis the IRS didn't see — usually buried in your year-end account statement or available from your broker on request.
4. Decide: agree, disagree, or partially agree.
The CP-2000 includes a response form with three checkboxes:
- I agree — sign, pay (or set up a payment plan), and you're done.
- I disagree — provide a written explanation with supporting documents.
- I partially agree — most cases land here. Agree to the items you can't defend, dispute the ones you can.
5. If you disagree — write a clear, calm, factual response.
The biggest mistake we see in DIY CP-2000 responses is over-explaining. The IRS examiner reviewing your response has a stack of these to get through. A clear one-page letter that says "Item 3 ($14,200 short-term capital gain from Schwab): The IRS computed this as $0 basis. Actual cost basis was $13,950 per attached Schwab year-end statement. Corrected gain: $250." is more effective than three pages of narrative.
What happens after you respond
If your response is clear and the documentation is strong, the IRS will typically issue a CP-2005 (case closed, no change) or a revised CP-2000 reflecting partial agreement. This usually takes 8-12 weeks.
If they don't accept your response, you'll receive a Notice of Deficiency — at which point you have 90 days to petition the U.S. Tax Court. This is a more serious posture and almost always warrants representation.
When to get help
You can handle a simple CP-2000 yourself. Where representation becomes worth the cost:
- The proposed liability exceeds $10,000
- You don't have clean documentation for the disputed items
- The notice involves business income, K-1s, or complex transactions
- You've already responded once and the IRS rejected it
- The CP-2000 has escalated to a Notice of Deficiency
Free CP-2000 review
If you got a CP-2000 and you're not sure how to respond, we'll review it for free. Send us the notice, your return, and any supporting documents, and we'll give you an honest assessment of what to do — including whether you need us at all.
Request Free Review →About the author: Jonathan C. Do is a tax attorney with 25+ years representing businesses and individuals in IRS audits, appeals, and U.S. Tax Court matters. He practices at Tax Resolution Center LLC in San Jose, CA.