The availability of relief depends on the usage of the property.

Usage of your property
Where to claim deductions

Let for rental income which is subject to Property Tax
Deduct mortgage interests from net assessable value under Personal Assessment (limit: reducing net assessable value to zero)

Occupied for use as the premises of your business
Deduct mortgage interests from your assessable profits under Profits Tax.

Occupied as your residence
Deduct home loan interest under Salaries Tax or Personal Assessment.

Vacant or occupied as dwelling by relatives rent-free (i.e. not for self-occupation or let-out)
No deduction