The CP2000 Playbook: How to Respond Without Overpaying
What a CP2000 is, why so many can be resolved with documentation, the reply-by date that actually controls, and the step-by-step response — including crypto and Form 1099-DA mismatches.
TL;DR
A CP2000 is a proposed adjustment, not a bill. The IRS matched information returns (1099s, W-2s, 1099-B) against your return and found a difference. Most differences are one of four things: missing basis on a brokerage sale, unreported retirement rollover, duplicated employer reporting, or timing mismatch — and, increasingly, crypto sales reported on Form 1099-DA without cost basis. Reply by the date printed on the notice. A well-documented response resolves many notices with little or nothing owed.
What a CP2000 actually is
A CP2000 is generated by the IRS Automated Underreporter (AUR) system when third-party information returns don't match what's on your Form 1040. It is not an audit. It is a proposed adjustment based on what the IRS can see. Most of what appears on the notice is mechanical — and most of it can be responded to with documentation rather than litigation.
The four most common causes
- Brokerage sales without reported basis. Pre-2011 holdings often lack broker-reported basis. The IRS sees the proceeds but not the cost, and defaults to treating the full proceeds as gain. Documentation of actual basis usually closes this.
- Retirement rollovers reported as distributions. A 1099-R with distribution code 1 or 7 can look like a taxable withdrawal when the full amount was actually rolled over within the 60-day window. Documentation of the receiving account and rollover date usually closes this.
- Duplicated employer reporting. Year-of-job-change W-2s can be reported in both state and federal numbers in ways that create apparent duplicates. A clean reconciliation usually closes this.
- Timing mismatches on 1099-NEC or 1099-MISC. Payer reports in one year, recipient recognized income in the year received. This requires either correcting the 1099 or showing the income was reported elsewhere.
Crypto and Form 1099-DA mismatches
Brokers began issuing Form 1099-DA for digital-asset sales made in 2025. For that first year, the form reports gross proceeds only — no cost basis. If the return did not report every sale on Form 8949, or reported it in a way that does not tie to the broker’s figures, the AUR system sees proceeds with nothing to offset them and can propose tax on the full amount.
- Match every 1099-DA line. Box 1f (proceeds) on each form must tie to a Form 8949 entry. Digital assets are reported in boxes G, H or I (short-term) and J, K or L (long-term) — not boxes C or F.
- Rebuild basis from records, not memory. Exchange CSVs, wallet addresses and transfer-in history. Under Rev. Proc. 2024-28, basis is tracked wallet by wallet, not in one universal pool.
- Watch transferred-in assets. Coins moved onto an exchange from elsewhere are generally noncovered, so the broker may show no basis (or the wrong one) even in later years. The return’s figure controls if the documentation supports it.
Basis reporting starts only for assets acquired after 2025, so mismatches on older holdings will keep appearing for years. Read the box-by-box Form 1099-DA guide →
Responding by the reply-by date
The deadline is the reply-by date printed on the notice — not a fixed number of days from when it reaches your mailbox. If that date is too tight to assemble documentation, call the number on the notice before it passes and ask for more time; do not let it lapse silently.
- Read the whole notice. The adjustment detail is usually in the middle pages, not the summary. Identify exactly which information returns triggered the adjustment.
- Pull transcripts. Account transcript and wage-and-income transcript show what the IRS actually has. Respond to what's on file, not what you remember.
- Draft a response letter. The notice includes a response form. Accept what is correct, dispute what is not, and attach supporting documentation for each dispute. Keep the tone factual.
- Send it in a way you can prove. The IRS now accepts CP2000 replies through its Documents Upload Tool (the fastest route, per the IRS), by fax to the number on the notice, or by certified mail to the address on the notice. Keep the confirmation.
- If the IRS does not accept the response. You may receive a revised notice, or a Statutory Notice of Deficiency (usually Letter 3219, with a Form 5564 waiver). The Notice of Deficiency starts a 90-day window to petition the U.S. Tax Court (150 days if addressed outside the U.S.). That deadline is strict and does not pause while you talk to the IRS — get representation before it runs. Appeals options are described in IRS Publication 5.
What not to do
- Do not ignore it. If you do nothing, the IRS will issue a Statutory Notice of Deficiency and assess the full proposed adjustment.
- Do not just pay. A large share of CP2000s are fully resolvable. Paying without responding removes your leverage and your refund rights.
- Do not call the 800 number and agree. The phone representative can note your response but cannot unwind an assessment. Respond in writing.
- Do not use email. The IRS does not accept CP2000 replies by email. Use the Documents Upload Tool, fax, or mail.
If a CP2000 just arrived, check the reply-by date first — then call us. We take on CP2000 engagements flat-fee, and file Form 2848 power of attorney the same day we engage.