Mortgage Interest Deductions when moved mid 2018

Hi there,

I moved mid 2018. Previously, I had a $350k principle balance I was paying interest on. Now I have an $850k balance (all numbers approx.).

 

I know that I can only deduct up to the first $750k of a mortgage with a principle balance >$750k, but since the first half of the year I was a lot less than that limit, will I still be getting credit for the amount >$750k at least until the end of the year, or will I only get the first $750k of the $850k mortgage for 6 months  regardless? 

 

This affects whether I will pay down to $750k or not until the end of the year. I cannot find anywhere that addresses this!

 

Thanks very much!