This is what Turbo Tax says about Home Debt Originating after December 15, 2017
The deduction for interest on home debt originating after December 15, 2017 is limited to the interest on $750,000 of debt ($375,000 for married filing separately). Enter the loan information for up to five qualified loans. The program will determine the average loan balance and will allocate interest to that loan based upon your entries.
I noticed on page 2 of the Ded Home Mort (Sched A Deductible Home Mortgage Interest Worksheet) form, that it was showing my average balance as the sum of both of the loans (the original + the refinance). This is wrong!
Based on what you said about the original and refinance, your average may be reflecting as $1.55mil ($750K+$800K) , rather than $775 [($750K+$800K)/2=$775]. Since the average is used to determine what percentage of interest is deductible (since any cash out was for home improvement), it may be reducing your interest deduction by 48% ($750K/$1.55 mil) instead of 96% ($750K/$775K=96%). I haven't figured out how to correct this, but, was able to manipulate some of the data in the second section of Part I, "Home Debt Originating after December 1, 2017" to drop my average balance below the $750K threshold which gave me 100% of my interest deduction. Other posts confirm that this has been an issue since 2019, so I would recommend contacting Turbo Tax for assistance.
