Bought and sold a home this year with a new mortgage above 750k. How do I calculate percentage of mortgage interest when only new mortgage above 750k?

[doT]

Question about home loan deduction.  Married filing jointly.  I had a home loan for a primary residence of 300k that originated in 2011 and was sold in 09/07/2018.  I also purchased a new primary residence with a home loan of 880k on 08/07/2018.  How do I calculate the home loan deduction for mortgage interest? My assumption is that I calculate the % of 750k/880k (0.852) and multiply this by the mortgage interest of the 880k loan.  I would not take a percentage of the loan that closed on 09/07/2018 and can deduct the full amount.  Does that make sense or do I have to treat all loans combined for entire year?  

[pk]

what you say stands to reason and should work.

Another way is to compute a blended loan principal  by counting month by month the amount owed and dividing it all by 12 to get an average  amount outstanding., especially if you had a mortgage outstanding every month of the year. -- may be more beneficial