(1) In the case of a nonresident individual, the tax imposed by section 39-22-104 shall be apportioned in the ratio of Colorado nonresident federal adjusted gross income to total federal adjusted gross income, both modified as provided in section 39-22-104.

(2)

(a) Colorado nonresident federal adjusted gross income means that part of the individual's federal adjusted gross income as determined pursuant to section 62 of the internal revenue code derived from sources within Colorado. Federal adjusted gross income of an individual shall be considered derived from sources within Colorado when such income is attributable to:

(I) The ownership of any interest in real or tangible personal property in Colorado;

(II) A business, trade, profession, or occupation carried on in Colorado;

(III) His distributive share of partnership or limited liability company income, gain, loss, and deduction determined under section 39-22-203;

(IV) His share of estate or trust income, gain, loss, and deduction determined under section 39-22-404;

(V) Income from intangible personal property, including annuities, dividends, interest, and gains from the disposition of intangible personal property to the extent that such income is from property employed in a business, trade, profession, or occupation carried on in Colorado. A nonresident, other than a dealer holding property primarily for sale to customers in the ordinary course of his trade or business, shall not be deemed to carry on a business, trade, profession, or occupation in Colorado solely by reason of the purchase and sale of property for his own account.

(VI) His share of subchapter S corporation income, gain, loss, credit, and deduction allocable or apportionable to Colorado.

(b) Compensation paid by the United States for service in the armed forces of the United States performed by an individual not domiciled in Colorado shall not constitute income derived from sources within Colorado.

(3)

(a) If the federal taxable income of two taxpayers, both of whom are nonresidents, is determined on separate federal returns, their Colorado taxable incomes shall be separately determined.

(b) If the federal taxable income of two taxpayers, both of whom are nonresidents, is determined on a joint federal return, their tax shall be determined on their joint Colorado nonresident federal taxable income.

(c) Repealed.

(4) In any case, where the nature of income earned by a nonresident individual is such as to render the computations described in subsections (1) to (3) of this section impracticable and where the books of account and records of the taxpayer do not clearly reflect the income subject to tax by this article, apportionment shall be made in accordance with section 39-22-303.5.