(A) This section applies solely for the purposes of computing the credit allowed under division (A) of section 5747.05 of the Revised Code and computing income taxable in this state under division (D) of section 5747.08 of the Revised Code.

(B) Except as otherwise provided under section 5747.212 of the Revised Code, all items of business income and business deduction shall be apportioned to this state by multiplying business income by the fraction calculated under division (B)(2) of section 5733.05 and section 5733.057 of the Revised Code as if the taxpayer‘s business were a corporation subject to the tax imposed by section 5733.06 of the Revised Code.

(C) If the allocation and apportionment provisions of sections 5747.20 to 5747.23 of the Revised Code or of any rule adopted by the tax commissioner, do not fairly represent the extent of business activity in this state of a taxpayer or pass-through entity, the taxpayer or pass-through entity may request, which request must be in writing accompanying a timely filed return or timely filed amended return, or the tax commissioner may require, in respect of all or any part of the business activity, if reasonable, any one or more of the following:

(1) Separate accounting;

(2) The exclusion of one or more factors;

(3) The inclusion of one or more additional factors which will fairly represent the business activity in this state;

(4) The employment of any other method to effectuate an equitable allocation and apportionment of such business in this state. An alternative method will be effective only with approval of the tax commissioner.

The tax commissioner may adopt rules in the manner provided by sections 5703.14 and 5747.18 of the Revised Code providing for alternative methods of calculating business income and nonbusiness income applicable to all taxpayers and pass-through entities, to classes of taxpayers and pass-through entities, or only to taxpayers and pass-through entities within a certain industry.