(a) The use of a combined report does not disregard the separate identities of the taxpayer members of the combined group. Each taxpayer member is responsible for tax based on its taxable income or loss apportioned or allocated to this state, which shall include, in addition to other types of income, the taxpayer member's apportioned share of business income of the combined group, where business income of the combined group is calculated as a summation of the individual net business incomes of all members of the combined group. A member's net business income is determined by removing all but business income, expense and loss from that member's total income, as provided in this section and section thirteen-d of this article.
(b) Components of income subject to tax in this state; application of tax credits and post-apportionment deductions. —
(1) Each taxpayer member is responsible for tax based on its taxable income or loss apportioned or allocated to this state, which shall include: