Paul
Please see my post number 3 at this link:
http://www.pprune.org/military-aviat...abatement.html
AFPS05 it is much more complicated. Firstly if you retire before 55 to go FTRS then you need to understand that an Early Departure Payment (EDP) is NOT a pension. Therefore, if you leave for FTRS before 55 then you will get NO yearly EDP until you retire from FTRS (or possibly at 55 depending on how the transition to AFPS15 is managed). On AFPS05 you DO get a pension at 55 and so if you retire now then you should get an abatable pension at 55. Now for the lump sum. If you retire with an EDP lump sum of £36k and your final Regular salary was £48k then you would have to leave the Service for 48/36ths years (ie. 1 year and 4 months) to keep all of that lump sum. If you left for 8 months and then wanted to rejoin under FTRS then you would have to pay back £18k (ie. 8/16ths or half) of your EDP lump sum. If you lose ANY of your lump sum during the FTRS process then you NEVER get it back again.
It is not good news I am afraid.
LJ