Patents Act, 1970
55. Term of patents of addition
(1) A patent of addition shall be granted for a term equal to that of the patent for the main invention, or so much thereof as has not expired, and shall remain in force during that term or until the previous cesser of the patent for the main invention and no longer:
PROVIDED that if the patent for the main invention is revoked under this Act, the court, or, as the case may be, the Controller, on request made to him by the patentee in the prescribed manner, may order that the patent of addition shall become an independent patent for the remainder of the term for the patent for the main invention and thereupon the patent shall continue in force as an independent patent accordingly.
(2) No renewal fees shall be payable in respect of a patent of addition, but if any such patent becomes an independent patent under sub-section (1), the same fees shall thereafter be payable, upon the same dates, as if the patent had been originally granted as an independent patent.