rbynaker
Level 14

IRC 163(h)(3) is your starting point.

(B)Acquisition indebtedness

(i)In general
The term “acquisition indebtedness” means any indebtedness which—

(I)
is incurred in acquiring, constructing, or substantially improving any qualified residence of the taxpayer, and
(II)
is secured by such residence.

 

As SJR alluded to, this may depend on how this is structured.  It needs to be a formal mortgage secured by the property (generally the mortgage is filed with the local court but state laws may vary).