I don't know if this will help with your question but it might. I took a normal retirement (not LEO or ATC or whoever else gets to retire at 50), at 34 yrs (only has to be 30) and Minimum Retirement Age (55 & 2 mos. for me). I took the combination of a lump sum and a series of monthly payments. When you take a series of monthly payments, if you are MRA (55) you avoid the 10% penalty. all you have to do is ensure the amount you chose is an amount that would last through 10 yrs (120 mos) of payments and you don't have to have taxes taken out either. The easiest way to figure the max you can take is divide your balance by 120 mos. That's what the TSP does. I only really wanted mine to last 10 yrs. so I've been withdrawing the max but I move in and out of the various funds and right now, without looking at my spreadsheet, it's up to 15yrs (lasting that is) or a little more if i don't increase the withdrawl rate. I really like doing it this way because I take more out this way rather than having it based on life expectancy (and then dying 15 years earlier), I can move the money around as I want/need, I don't have to have taxes taken out if I don't want to (and I haven't had to pay any yet except on the lump sum the first year), and the fees are so small they're not even noticeable unlike most brokerage costs. You can change the amount once a year but look real close at what you're doing because you're stuck with whatever decision you make for that year. I would move all my money into the G Fund while the paperwork is being processed. Then you don't really have to worry about your balance changing (going down) before the TSP does their thing. I don't know if this helped, but if not you, maybe it will help someone else. Regards, The Walleye Slayer