Question RE: refinanced mortgage balances vs. grandfathered balances

[marman0614]

Balance of mortgages taken prior to Dec.2017 = $865K.   Refinanced mortgage balances on Dec.2019.  The new total is $800K.    Since the balances prior to 2017 were "grandfathered" (covered under the $1.0mm threshold),  is the new balance of $800K also grandfathered as a refinance...or is it considered a brand new loan, therefore, it falls under the threshold of $750K for mortgage loans taken after Dec.2017?

Help?   Thank you.

[BarbaraW22]

If you refinance a mortgage that was originally taken out after 10/13/1987, the refinanced mortgage will be considered "home acquisition debt" up to the amount of mortgage principal just before you refinanced. Any additional debt not used to buy, build or substantially improve a qualified home isn't home acquisition debt.

Per IRS Publication 936, home acquisition debt originated after 12/15/2017 is debt that is secured by your main home or second home and is limited to $750,000.