The short answer
Usually routine. A CP2000 is not an audit. It means the income on your return did not match a form a third party sent the IRS. Sometimes the IRS is right and you owe a small amount. Sometimes they are missing information and you owe nothing. Either way, do not ignore it and do not just pay it.
What a CP2000 actually is
A CP2000 comes out of the IRS automated underreporter program. A computer compared the income reported on your return against the W-2s, 1099s, and other forms that employers, banks, and brokerages filed under your Social Security number. When the totals do not match, the system generates a notice with a proposed adjustment.
The important word is proposed. A CP2000 is not a bill and it is not an audit. It is the IRS showing its work and asking you to confirm or correct it. You have the right to disagree.
Why you might owe nothing at all
The most common harmless cause is missing cost basis on an investment sale. When you sell stock or a fund, the brokerage reports the gross proceeds to the IRS. If the basis, what you originally paid, is not also reported, the IRS computer can treat the entire sale as gain. A $40,000 sale of shares you bought for $38,000 looks like $40,000 of income to the automated system and $2,000 of income on a correct return.
When you respond with the basis, the proposed tax shrinks or disappears. This is why paying the notice without checking can mean handing the IRS money you do not owe.
Why you should not simply pay it
A CP2000 includes a response form with an agree option. Signing it accepts the proposed tax. If the proposal is wrong in your favor, agreeing locks in a number that was never correct. It can also flow downstream: an accepted federal change often triggers a matching state notice, so a wrong number gets paid twice.
Equally, ignoring it is the worst option. If you do not respond by the deadline, the IRS finalizes the proposed amount, and unwinding a finalized assessment is far harder than answering a proposal.
What to do
- Read the notice for the exact deadline, usually 30 days from the date printed on it.
- Compare each flagged item to your filed return and find what the IRS thinks is missing.
- Gather the underlying documents, especially brokerage statements showing cost basis.
- Respond by the deadline, agreeing only if the proposal is genuinely correct.
This is general guidance, not advice for your specific situation, and it is current as of when it was written. Tax law changes and the right answer depends on your full picture. That is what the first call is for.
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