6.—(1) If before the end of the contribution period the contributions payable under paragraph 5 cease to be payable otherwise than by reason of the person's—
(a)dying; or
(b)becoming incapacitated before attaining the age of 60,
he may by giving written notice to the Department within 3 months after the cessation elect to complete payment of the additional contributions by making a lump sum payment under this paragraph.
(2) Subject to paragraph 3 of Schedule 3, the amount of the payment is the total of the contributions that would have been payable for the remainder of the contribution period.
(3) A lump sum payable under this paragraph may, if he agrees, be set off against any retirement lump sum to which the person is entitled.