(b)where it relates to investment allowance, be carried forward to the assessment year commencing on the 1st day of April, 1993 and the balance of the investment allowance, if any, still outstanding shall be carried forward to the following assessment year and where the period of eight years has expired before the portion of such balance is adjusted, the said period shall be extended beyond eight years till such time the portion of the said balance is absorbed in the profits and gains of the business of the domestic company.