Thank you for the note, Shikhar. I used two life-expectancy assumptions, both realistic for me personally and my culture. The reason for two is that I wanted to see how sensitive the model was to end date. Turns out it is, but less so than for interest rate assumption. Consult your actuary for your own estimates. Your mileage may vary.

If you’re looking at opportunity cost, then something is wrong. You should not be drawing assets to defer your start date. Most people are earning money until their start dates, living off current income. My brother-in-law, who is still working, was making plenty of money right through age 70. When he finally filed, they gave him all his back pay in a lump sum and then started him on his highest payout level. If you have liquid assets while you’re working, of course you should be investing those according to your risk profile.