(a) DeterminationFor purposes of this part, the term “determination” means—
(1)
a decision by the Tax Court or a judgment, decree, or other order by any court of competent jurisdiction, which has become final;
(3) a final disposition by the Secretary of a claim for refund. For purposes of this part, a claim for refund shall be deemed finally disposed of by the Secretary—
(b) Taxpayer
Notwithstanding section 7701(a)(14), the term “taxpayer” means any person subject to a tax under the applicable revenue law.
(c) Related taxpayerFor purposes of this part, the term “related taxpayer” means a taxpayer who, with the taxpayer with respect to whom a determination is made, stood, in the taxable year with respect to which the erroneous inclusion, exclusion, omission, allowance, or disallowance was made, in one of the following relationships:
(Aug. 16, 1954, ch. 736, 68A Stat. 339; Pub. L. 94–455, title XIX, § 1906(b)(13)(A), Oct. 4, 1976, 90 Stat. 1834.)