Secured Loan Requirement. For the interest expense to be deductible, the loan must be secured by the financed property.
You can deduct interest paid on a timeshare under certain circumstances. Here is what TurboTax says: Can I deduct the mortgage interest on a timeshare?
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.