Key Takeaways A CP2000 notice is generated by the IRS's Automated Underreporter (AUR) program when income reported by third parties does not match your tax return A CP2000 is not an audit — it is a proposed adjustment that you can agree with, partially agree with, or fully dispute Common triggers include unreported 1099 income, W-2 discrepancies, stock sales, and retirement distributions You typically have 30 days to respond, and your response determines whether the IRS assesses additional tax Even if you partially agree, working with a tax resolution professional can help minimize the additional tax and penalties What Is IRS Notice CP2000? IRS Notice CP2000 is a proposed adjustment notice generated by the IRS's Automated Underreporter (AUR) program. The AUR system is one of the IRS's most powerful compliance tools — it compares the income, deductions, and credits reported on your tax return against information returns (W-2s, 1099s, K-1s, etc.) filed by employers, banks, brokerage firms, and other entities that paid you money during the tax year. When the AUR system detects a discrepancy between what was reported to the IRS by third parties and what you reported on your return, it generates a CP2000 notice proposing changes to your tax. The notice includes a detailed comparison of the income the IRS has on file versus what you reported, along with the proposed additional tax, penalties, and interest that would result from the adjustment. It is important to understand that a CP2000 is not technically an audit. It is a computer-generated proposed adjustment based on a mismatch in reported information. No IRS examiner has reviewed your return in detail or made a judgment about your tax situation. However, if you do not respond appropriately, the IRS will assess the proposed additional tax and begin collection — just as if...