§ 33. Consolidated returns. Corporations which are affiliated may, if
authorized, and shall, if required, by the director of finance, under
regulations prescribed by the director of finance, make a consolidated
return for the purpose of this part. In any case in which a tax is
assessed upon the basis of a consolidated return, the total tax shall be
computed in the first instance as a unit and shall then be assessed upon
the respective affiliated corporations in such proportions as may be
agreed upon among them, or in the absence of any such agreement, then on
the basis of the net income properly assignable to each.