Contributions made in the taxable year ending on the date of distribution or transfer and the 4 prior taxable years by the distributor or transferor corporation in excess of the amount deductible under section
170
(b)(2) for such taxable years shall be deductible by the acquiring corporation for its taxable years which begin after the date of distribution or transfer, subject to the limitations imposed in section
170
(b)(2). In applying the preceding sentence, each taxable year of the distributor or transferor corporation beginning on or before the date of distribution or transfer shall be treated as a prior taxable year with reference to the acquiring corporation’s taxable years beginning after such date.