Deductions & credits

Thank you @LindaS5247 for the detailed and thoughtful reply.  So am I understanding correctly that the $1,000,000 limit of our pre-Dec 16, 2017 loan, and the associated interest deduction benefits thereof, were undercut/eliminated when we took out a separate mortgage on a separate home after Dec 15, 2017?

 

I'm not tracking why we wouldn't at least get to fully deduct the interest on the mortgage for our Main Home (pre-Dec 16, 2017 subject to $1,000,000 limit) even if we were required to pro-rate the deduction for the interest on our Second Home (post-Dec 15, 2017 subject to $750,000 limit).  Instead, the worksheet appears to be lumping both loans into the post-Dec 15, 2017 category that is subject to the $750,000 limit and ignoring the higher $1,000,000 limit for the pre-Dec 15, 2017 mortgage on our Main Home?