Ah, I see what you did. I did only part of it. And I made a simplifying assumption
You applied a 2% COLA to the early amount starting at age 62, in which case at age 66 it will be $677/mo. You did the same for the reported FRA benefit, so that when SSA says (today) it will be 833/mo, you assume that the FRA benefit will also grow by 2% COLA, so that when you actually get to 66 the FRA benefit will have ballooned to 902/mo. Clever--I didn't think about that. I applied the COLA only after the checks began--either age 62 or age 66.
Interestingly, the thing I checked by spreadsheet against (
http://web.bryant.edu/~rmuksian/textbook/Breakeven62vsNormal.xls
) _also_ applies COLA only after the checks begin. So maybe both him and me made this mistake.
If it is a mistake.
When I compare what SSA sent to me on Feb 2008 vs. Feb 2009, my 2009 age early (62) payment was 3.1% higher that the 2008 number, but FRA (66) payment was only 1.2% higher. How can this be? Shouldn't these have gone up by the same percentage? Indeed, shouldn't the 66 amount have gone up even more due to compounding? To further confuse me, the 2008 COLA was 5.8% and the 2009 COLA was 0.0%. So where did the 3.1% come from? Certainly nothing else has changed---I'll still have turned 62 on the same date, and have turned 66 on the same date, and I've hit the caps.
Arrrggghhh! They also said that if I deferred to age 70, the difference between the 2008 amount and the 2009 amount was $3/mo or 0.1%.
BTW, my simplifying assumption was that the COLA gets applied monthly rather than annually. At low rates, this does not introduce much of an error.