Indiana Code Title 6. Taxation § 6-2.5-2-1

Sec. 1. (a) An excise tax, known as the state gross retail tax, is imposed on retail transactions made in Indiana.

(b) The person who acquires property in a retail transaction is liable for the tax on the transaction and, except as otherwise provided in this chapter, shall pay the tax to the retail merchant as a separate added amount to the consideration in the transaction. A retail merchant that has either physical presence in Indiana as described in subsection (c) or that meets one (1) or both of the thresholds in subsection (d) shall collect the tax as agent for the state.

(c) A retail merchant has physical presence in Indiana when the retail merchant:

(d) A retail merchant that does not have a physical presence in Indiana shall, as an agent for the state, collect the gross retail tax on a retail transaction made in Indiana, remit the gross retail tax as provided in this article, and comply with all applicable procedures and requirements of this article as if the retail merchant has a physical presence in Indiana, if the retail merchant meets either of the following conditions for the calendar year in which the retail transaction is made or for the calendar year preceding the calendar year in which the retail transaction is made:

(e) A marketplace facilitator must include both transactions made on its own behalf and transactions facilitated for sellers under IC 6-2.5-4-18 for purposes of establishing the requirement to collect gross retail tax without having a physical presence in Indiana for purposes of subsection (d). In addition, except in instances where the marketplace facilitator has not met the thresholds in subsection (d), the transactions of the seller made through the marketplace are not counted toward the seller for purposes of determining whether the seller has met the thresholds in subsection (d).