Ind. Code § 6-5.5-5-2
A combined return must include the adjusted gross income of all members of the unitary group, even if some of the members would not otherwise be subject to taxation under this article. The department may require a member of a unitary group to provide any information that is needed by the department to determine the unitary group's apportioned income under this article. However, income of corporations or other entities organized in foreign countries, except a foreign bank (or its subsidiary) that transacts business in the United States, shall not be included in the combined return. In calculating adjusted gross income, the taxpayer shall eliminate all income and deductions from transactions between entities that are included in the combined return. In addition, in computing receipts for the apportionment factor under IC 6-5.5-2-4(2), the taxpayer shall eliminate receipts between unitary group members included in the combined return.
IC 6-5.5-5-2