The loan must be a perfected mortgage. A mortgage is a loan on real property that says the lender can seize the property if you don't pay. Perfected means that the loan is filed with the county clerk's office and listed as a lien on the property, so that is shows up as lien against the property in a property search.
Now, in the case of a 2-week time share, this might mean that a single property would have at least 26 liens listed against it in the county records. That is one way the time share company might manage their loans. But if the loan is not listed as a property lien with the country, and the timeshare lender manages things in-house, then it is not a deductible mortgage.
