A CP2000 is not a bill. It's a notice of proposed changes to your tax liability. You have 30 days to reply to the notice with your explanation of why you should not be liable for the additional taxes. Obviously, if you were never paid by your spouse's corporation, then the 1099Misc is erroneous, and your explanation may be sufficient. If not, then the IRS will send you a Notice of Deficiency, and that is the tax bill. At which point you would have 90 days to petition the U.S. Tax Court for a resolution of the dispute.
The CP2000 should provide you with instructions on the minimum response, and how to return your response. I suggest that you may want to send the letter certified mail, so that you can prove it was sent and received.
That's pretty much the whole process at this point.
Note: If it makes you feel any better, I've received CP2000 notices in the past for more than $100,000. I have provided a careful explanation of why the amount to be assessed is erroneous, and the IRS has accepted, and cancelled the entire proposed bill. So, just be really careful and thorough with your explanation.
And, timely -- your response must be received by Oct 21.
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