You do not need Premier and you may not even need Deluxe. You can only deduct the interest if the boat is considered a 2nd home. And even if it is, if you don't have enough itemized deductions (more than the standard deduction) and you take the standard deduction, you may be able to use the Free Edition.
You can always start in Free and upgrade if you need to later.
You're allowed to deduct the interest on a loan secured by your main home (where you ordinarily live most of the time) and a second home.
A mobile home, RV, house trailer, or houseboat that has sleeping, cooking, and toilet facilities counts as a main or second home, and as long as it meets all the other requirements for deducting mortgage interest, you can claim the interest like an immovable home.
Go here for more info on which forms are included in TurboTax Free Edition.
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