(a) In the event two or more corporations file federal income tax returns on a consolidated basis, and in the event that all of such corporations derive all of their income and expenses from sources within Kansas, then, and in such events, such corporations shall file consolidated returns for purposes of determining their Kansas income tax liability the same as if such corporations were one corporation.

(b) The director may permit or require any group of affiliated corporations to file consolidated returns under regulations to be promulgated by the director where the director determines, that the filing of such consolidated returns is necessary to clearly reflect the Kansas taxable income of the affiliated group. For purposes hereof, any affiliated group means any group of corporations permitted to file a consolidated return for federal income tax purposes.