first tier tax

For purposes of this subchapter, the term “first tier tax” means any tax imposed by subsection (a) of section 4941, 4942, 4943, 4944, 4945, 4951, 4952, 4955, 4958, 4966, 4967, 4971, or 4975.

Source

26 USC § 4963(a)

Scoping language

For purposes of this subchapter