Once you hit NZ*E (1500 SP over a 12 month period), the SP count resets and you have 12 months to get another 1350 SP to requalify for it the following year. If you get more than 1350 (but less than 2400) in that 12 month requal period, the excess rolls over to the following 12 month period. If you earn 2400 or more SP in that 12 month requal period, you get a banked year.