I have a mortgaged rental property that needs to be torn down; a new one built. If the mortgage is moved to a personal residence heloc, how is this handled on taxes?

[brizendin0]

Is the mortgage transfer from the rental property to a personal residence heloc, considered as part of the rental property basis, a loss, or an expense to the new structure built?

[Critter]

The old mortgage has nothing to do with any of those things. The fact you move the debt to a different residence has no bearing on the original property. 

[Hal_Al]

The mortgage balance has nothing to do with the rental property basis or  the new structure to be built.
Since the interest paid on the loan is no longer attributable to the rental unit, it is no longer deductible on Schedule E (rental income and expenses). It is deductible on Schedule A (itemized deductions, including mortgage interest on your residence).

[Bees]

technically would not be deductible in 2019 since it  does not improve the underlying property. How about if he  formed   an LLC?