(1) The application of Part IV to and in relation to a person to whom this Part applies is subject to this section.
(3) For the purpose of determining the amount of contribution payable by a person to whom this Part applies, the age at which he became a person to whom this Part applies shall be deemed to be the age at which he became a contributor prior to becoming entitled to a pension.
(4) Where the new category number of a person to whom this Part applies is a lower number than his previous category number, he may, by notice in writing given to the Board within 4 months after he became a person to whom this Part applies, elect to be treated as if his new category number were the same as his previous category number, and, if he so elects, his category number shall, upon his becoming a person to whom this Part applies and until the category number applicable to him under section 4A is a number higher than his previous category number, be deemed, for the purposes of this Act, to be a number the same as his previous category number.
(5) In subsection (4):
"new category number" , in relation to a person to whom this Part applies, means the category number of the person at the time when he became a person to whom this Part applies.
"previous category number" , in relation to a person to whom this Part applies, means the category number of the person immediately before he became a pensioner or, if that category number would, if this Act, and the Defence Forces Retirement Benefits Regulations, as in force at the time when he became a person to whom this Part applies, had been in force immediately before he became a pensioner, have been a different number, that different number.
(6) The reference in the definition of previous category number in subsection (5) to the category number of a person immediately before he became a pensioner shall, in the case of a person who became a pensioner before 14 December 1959, be read as a reference to the number of units for which the person was last contributing to the Fund before he became a pensioner.
(7) Nothing in Part III of the Defence Forces Retirement Benefits Act 1959 - 1966 , Part IV of the Defence Forces Retirement Benefits Act 1962 - 1963 or Part IV of the Defence Forces Retirement Benefits Act 1963 - 1965 shall be construed as affecting the amount of contributions payable by a person to whom this Part applies.