Pass-through partner.
(5) Pass-through partner. The term pass-through partner means a pass-through entity that holds an interest in a partnership. A pass-through entity is a partnership required to file a return under section 6031(a), an S corporation, a trust (other than a wholly-owned trust disregarded as separate from its owner for Federal income tax purposes), and a decedent's estate. For purposes of this paragraph (a)(5), a pass-through entity is not a wholly-owned entity disregarded as separate from its owner for Federal income tax purposes.