Indiana Code Title 6. Taxation § 6-6-11-13

Sec. 13. (a) A boat owner shall pay the boat excise tax for a registration year to the bureau of motor vehicles.

(b) The tax set forth in subsection (a) must be paid at the same time that the boat owner pays or would pay the registration fee and vehicle excise taxes on motor vehicles under IC 9-18 (before its expiration), IC 9-18.1, and IC 6-6-5. When the boat owner pays the tax and fees, the owner is entitled to receive the registration decals.