If you rent it out and don't live there yourself, you can claim property taxes on your rental as an expense against your rental income.
However, if you're renting out a portion of your own home, you're eligible for a prorated deduction for the portion of the home you live in, with the remainder written off as a rental expense.
Either way, enter the property tax where you enter all your other rental expenses. If you also live there, we'll calculate your personal deduction based on the portion you live in. Don't enter your property tax again in the Deductions & Credits section, as we've already taken care of that in the rental section.