(1) The top-up annual rate of the pension on the key day when the invalidity pensioner is under 60 is the rate worked out using the formula:
(2) In subsection (1):
"invalid's period of qualifying service " means the number of whole years in the period (subject to subsection (3)) for which the invalid was a member of the Permanent Forces or continuous full-time Reservist.
How to deal with multiple periods of service
(3) For the purposes of subsection (2), if:
(a) there are 2 or more periods (the serving periods ) when the invalid was a member of the Permanent Forces or a continuous full-time Reservist; and
(b) the serving periods are separated by one or more periods (the non-serving periods ) when the invalid was neither a member of the Permanent Forces nor a continuous full-time Reservist;
take account of only the serving period or serving periods after the latest non-serving period.