What is a CP2000 notice from the IRS?

A CP2000 is a proposed adjustment notice, not an audit — the IRS matched your return against third-party documents (W-2s, 1099s) and found a discrepancy. It proposes additional tax, interest, and sometimes penalties. You have 60 days to respond: agree and pay, disagree with documentation, or request more time. Ignoring it causes the IRS to assess the proposed amount automatically.