C.R.S. § 39-22-342

As used in this subpart 3, unless the context otherwise requires: (1) “Electing pass-through entity” means, with respect to a taxable period, an S corporation or partnership that has made the election under section 39-22-343 with respect to the taxable period. (2) “Electing pass-through entity owner” means, with respect to an S corporation, a shareholder of the S corporation and, with respect to a partnership, a partner in the partnership; except that a partner does not include a C corporation that is unitary with the partnership. (3) “Income attributable to the state” means, with respect to an S corporation, the portion of the items of income, gain, loss, or deduction of the S corporation apportioned or allocated to this state in accordance with the provisions of section 39-22-321 (1) and (2), and, with respect to a partnership, the portion of the income, gain, loss, deduction, or credit of the partnership derived from sources within Colorado determined in accordance with the provisions of section 39-22-203 . (4) “Income not attributable to the state” means all items of income, gain, loss, or deduction of an electing pass-through entity other than income attributable to the state. (5) “Resident electing pass-through entity owner” means an electing pass-through entity owner that is a resident of Colorado as defined in section 39-22-103 (6), (7), (8), (9), and (10). (6) “Taxable period” means any taxable year or portion of a taxable year during which a corporation is an S corporation or a noncorporate entity is a partnership.