1. (a) If the minimum taxable income required to be reported under article 9-A of the Tax Law is for a period different from the period covered by the taxpayer's Federal income tax return, the taxpayer's minimum taxable income must be prorated to correspond with the period covered by the report under article 9-A of the Tax Law. The prorated minimum taxable income is computed as follows:

   1. (1) divide minimum taxable income, as determined in section 3-4.2 of this Subpart, by the number of calendar months, or major parts thereof, covered by the return for Federal income tax purposes; and
   2. (2) multiply the result by the number of calendar months, or major parts thereof, covered by the report under article 9-A of the Tax Law.
2. (b) The method of computing minimum taxable income set forth in subdivision (a) of this section applies to taxpayers reporting on either a calendar year or a fiscal year basis for Federal income tax purposes.
3. (c) If in the opinion of the Commissioner, the method described in this section does not properly reflect the taxpayer's minimum taxable income for purposes of article 9-A of the Tax Law during the period covered by its report, the Commissioner may determine minimum taxable income solely on the basis of the taxpayer's income during such period.

Tax Law, § 208(8-B)(e)