Indiana Code Title 6. Taxation § 6-5.5-5-1

Sec. 1. (a) Except as provided in this section, a unitary group consisting of at least two (2) taxpayers shall file a combined return covering all the operations of the unitary business and including all of the members of the unitary business.  However, only one (1) combined return needs to be filed, as provided in IC 6-5.5-6-1.

(b) If the department or taxpayer determines that the result of applying this section or article do not fairly represent the taxpayer's income within Indiana or the taxpayer's income within Indiana may be more fairly represented by a separate return, the taxpayer may petition for and the department may allow, or the department may require, in respect to all or a part of the taxpayer's business activity any of the following:

For purposes of this subsection, “tax items” means gross income, deductions, gains, losses, and credits used in computing the tax under this article, except the term shall exclude dividends or other distributions regardless of whether the amounts are deductible or taxable in computing taxable income under the Internal Revenue Code.

(c) Income apportioned under this article must reflect a change in adjusted gross income that is required to comply with a department order under this section.