Where M/s Garden Reach Shipbuilders and Engineers Limited, Kolkata (hereinafter referred to as (GRSE) is liable to pay tax under section 14, it may, for the purpose of determining its taxable contractual transfer price on which tax is payable under sub-section (1) section 18 during any period, deduct under clause (d) of sub-section (2) of that section 18 from the total contractual transfer price received or receivable by him on or after 1st day of April, 2005 on the construction of vessel that part of such contractual transfer prior which represents contractual transfer of goods involved in the execution of works contract in West Bengal, where the execution of such works contract is undertaken pursuant to a cost plus remuneration contract.