Key Takeaways
- A CP2000 is a proposed adjustment, not an audit — but it requires prompt attention
- Most CP2000s result from income reported by third parties (employers, banks, brokers) that does not appear on your return
- Common triggers: missing 1099-NEC, forgotten bank interest (1099-INT), unreported stock sales (1099-B)
- The IRS uses automated matching programs to compare your return against third-party information
- Not reporting income does not prevent the IRS from learning about it
Understanding the CP2000 Notice
A CP2000 notice is a letter from the IRS indicating a discrepancy between what you reported on your tax return and the information the IRS received from third parties. It is not an audit — it is a proposed adjustment. However, it should be taken very seriously and dealt with promptly.
The most common reason for receiving a CP2000 is underreported income. The IRS compares your return against information returns (W-2s, 1099s, etc.) filed by employers, banks, brokerage firms, and other payers. When the numbers do not match, the IRS sends a CP2000 to propose adjustments.
Common Triggers for CP2000 Notices
Several types of income frequently trigger CP2000 notices. Missing 1099-NEC income from freelance or contract work is common — your client reports the payment to the IRS, but you forget to include it on your return. Forgotten interest income (1099-INT) from bank accounts is another frequent cause, as banks automatically report even small amounts of interest.
Stock sales reported on 1099-B from brokerage accounts are also a major trigger, especially when taxpayers report cost basis incorrectly or omit sales entirely. Other common sources include unreported dividend income (1099-DIV), retirement distributions (1099-R), and gambling winnings (W-2G).
How Third-Party Reporting Works
The IRS receives copies of most information returns electronically. Employers file W-2s, banks file 1099-INTs, brokerages file 1099-Bs, and clients file 1099-NECs. The IRS then runs automated matching programs to compare this third-party data against your filed tax return. When discrepancies are found, the CP2000 notice is generated automatically.
This means the IRS often knows about your income before you even file your return. Simply not reporting income does not prevent the IRS from discovering it.
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