qualified housing interest
(1) In general The term “qualified housing interest” means interest which is qualified residence interest (as defined in section 163(h)(3)) and is paid or accrued during the taxable year on indebtedness which is incurred in acquiring, constructing, or substantially improving any property which— (A) is the principal residence (within the meaning of section 121) of the taxpayer at the time such interest accrues, or (B) is a qualified dwelling which is a qualified residence (within the meaning of section 163(h)(4) ). Such term also includes interest on any indebtedness resulting from the refinancing of indebtedness meeting the requirements of the preceding sentence; but only to the extent that the amount of the indebtedness resulting from such refinancing does not exceed the amount of the refinanced indebtedness immediately before the refinancing.