Got a Crypto CP2000 Notice? How to Respond in Time
A Notice Isn't a Verdict
If you traded crypto and received a notice from the IRS proposing additional tax, you are not alone, and it is not the end of the conversation. As Form 1099-DA reporting ramps up, more crypto traders are seeing CP2000 notices land in their mailbox for the first time.
A CP2000 can look alarming. It states a proposed tax amount, sometimes a large one, and it comes with a deadline. But a CP2000 is not an audit and it is not a bill. It is a proposed adjustment based on a mismatch the IRS's automated systems detected, and you have the right to respond with documentation before anything is finalized. This guide walks through exactly what to do, and by when.
What a CP2000 Actually Is (and Isn't)
A CP2000 notice comes from the IRS's Automated Underreporter (AUR) program. It compares the information returns filed on your behalf, including 1099-DA forms from exchanges, against what you reported on your tax return. When the two don't match, the system generates a notice automatically, without a human examiner reviewing your file first.
That matters because it means the number on your CP2000 is not a final determination of what you owe. It is what the system calculated using only the data it had, which for crypto is often just gross proceeds with no cost basis attached. If your actual gain was smaller than the reported proceeds (or there was no gain at all), the notice can be reduced or eliminated once you respond with documentation.
Here is what that looks like in practice. Say you sold crypto for $90,000 that you originally bought for $80,000. Your actual gain is $10,000, and that's what belongs on your return. But the exchange's 1099-DA reports the $90,000 in proceeds with no basis attached, so the IRS's system sees a $90,000 figure with nothing to reconcile it against and flags a mismatch. Your return was correct. The notice exists because the exchange couldn't see what you paid to acquire the asset, not because you made an error.
For a deeper look at why 1099-DA reporting creates this mismatch in the first place, see our earlier posts on what Form 1099-DA reports and why it can trigger IRS review. This guide picks up from there: what to do once the notice is already in your hands.
Reading Your Notice: What to Look For
Before responding to anything, locate three details on the notice itself:
The notice date. This is what starts your response clock, not the day the letter arrived in your mailbox.
The specific line items in question. The notice will identify which forms and amounts triggered the mismatch, often referencing the exchange or broker that issued the 1099-DA.
The proposed changes. This includes the additional tax proposed, any accuracy-related penalty the system calculated, and the interest accrued so far.
Confirm whether the notice matches a transaction you recognize. Sometimes the mismatch is legitimate cost basis that wasn't reported; other times it can reflect a duplicate report, an error by the exchange, or income already reported elsewhere on your return.
The Clock: Your Response Window
You typically have 30 days from the date printed on the notice to respond, or 60 days if you live outside the United States. This window is shorter than it feels once mail delivery time is factored in, so treat the notice date, not the day you opened the envelope, as your starting point.
If you need more time, you can call the number listed on the notice to request an extension before the deadline passes. Extensions are not guaranteed, so it's worth starting your documentation process as soon as the notice arrives rather than waiting to see if one is approved.
Building Your Response Packet
The strength of your response depends entirely on the quality of your documentation. A complete packet typically includes:
Full transaction records for the assets in question. This means the acquisition date, acquisition cost, and disposition details for every unit involved, not just the exchange that issued the 1099-DA. If you transferred crypto between exchanges, moved assets to a self-custody wallet, bought on one platform and sold on another, or have any DeFi activity, that history needs to be traceable too. This is a visibility problem more than a tax problem: the exchange issuing the 1099-DA can only report what happened on its own platform, so anything that happened elsewhere has to come from your own records.
Your accounting method, applied consistently. The IRS recognizes FIFO and Specific Identification, which includes HIFO and LIFO as lot-selection strategies, as accepted approaches for US crypto reporting. DeFi Tax currently supports FIFO, LIFO, and HIFO. Whatever method you used needs to be applied consistently and documented.
The gain or loss data needed for Form 8949 and Schedule D, reflecting your actual cost basis rather than just the proceeds figure from the 1099-DA. You or your preparer will use this data to complete the forms themselves.
A written explanation connecting the documentation to the specific discrepancy the notice identifies. The IRS response form usually has space for this, and clarity here matters more than length.
Agree, Disagree, or Partial: Choosing Your Response
If the notice is correct and you have additional income or deductions to report, file Form 1040-X with "CP2000" written at the top, along with the signed response form.
If you disagree, submit your documentation along with a written explanation of why the proposed amount is incorrect. Include your cost basis records, the accounting method used, and any supporting statements from exchanges or wallets.
If only part of the notice is correct, you can agree to some items and dispute others in the same response. Be specific about which line items you're addressing.
If you disagree with the outcome after responding, a qualified tax professional or IRS Enrolled Agent can advise on next steps including the appeals process.
What Happens If You Miss the Deadline
If you don't respond in time, the IRS generally treats the proposed changes as agreed and moves toward assessing the tax. The next step is typically a Statutory Notice of Deficiency (CP3219A), which gives you 90 days to petition U.S. Tax Court, a deadline that cannot be extended. Missing that window as well means the proposed tax becomes final and moves to collections.
This is why responding within the initial window, even with a partial or preliminary response, is worth prioritizing over waiting until your documentation is perfect.
The Bottom Line
A CP2000 notice is a starting point for a conversation with the IRS, not the final word on what you owe. The taxpayers who resolve these notices quickly are the ones who can produce complete transaction records and a consistently applied accounting method without having to reconstruct everything from scratch under deadline pressure.
This wave of notices is also just getting started. 2025 was the first year exchanges reported gross proceeds on Form 1099-DA, and cost basis reporting for covered assets doesn't phase in until 2026. Until it does, this mismatch is structural, not incidental, and more traders will see it before it resolves on its own.
DeFi Tax is designed to keep that documentation ready before a notice ever arrives: full transaction history across wallets and exchanges, and cost basis data calculated under your chosen method, organized in a format built for exactly this kind of response. DeFi Tax produces the reportable data; you or your tax preparer remain responsible for how that data is entered onto your actual tax forms.