更新1:
I had an extensive break in service prior to returning to the military. As such, my actual TIS is over 4 years, but my LES is paying me as an 8 year soldier (personnel at finance verified the accuracy of this; apparently IRR time counts towards it.) So in order to qualify for a 20 year pension (since my DIEMS grandfathers me into the old retirement plan), do I need to fulfill an additional 16 years of service, or do I only need to serve 12 more years and hit that 20 year mark on my LES?