As one who has been preparing income taxes for over 30 years, I should be able to answer your questions regarding interest and personal property taxes.
Mortgage interest deduction - An AS will qualify as a second residence because it has a galley and a head. The interest you pay on the loan for a second residence is deductible as mortgage interest.
Personal property taxes - Personal property tax is deductible if it is a state or local tax that is charged on personal property, based on the value of the personal property, and is charged on a yearly basis. Vehicle license fees based on weight, model, year or horsepower is not deductible.
Here in NH we have no sales taxes, however over a five year period we will pay at least 8% of the cost of a vehicle in personal property taxes. The tax we pay is deductible where as a sales tax is not.
Good luck on your taxes.
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