After you file

This might be one of those...What did you really mean ? situations.

 

a) .....the IRS thinks you owe them another $350,000 in actual taxes (which is what you said), and may imply selling a home for ~$1million or more .

 

or instead

a)  Does the IRS think you owe a tax on $350,000 more income?  (i.e. sold home for ~$350,000) 

 

____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*