Subject: Re: Purchasing service credit at retirement age?
Purchasing 5 more years of service credit would cost an estimated $58,638 and would increase my monthly benefit by $334.
Thus, it would take 176 months to break even - around the age of 80.


I would consider that to be in immediate annuity of the $58k. You could run your details through an annuity calculator like the Schwab one linked below and I think you will find it is no better,and likely slightly worse, than what you could simply buy on the open market. If an annuity meets the needs of your personal situation then you may want to look elsewhere than buying the years.

https://www.schwab.wallst.com/...


BUT - how do I apply the cost of that missing $58k lump sum (I have both IRAs, 457/401 and non-tax advantaged accounts to pull from if need be) to this calculation? Is there any ballpark rule-of-thumb to simplify this, just as a reality check?

This is highly dependent on an individual's situation and risk tolerance. Any "rule of thumb" may not apply to a persons unique circumstances and personal values. Some good discussion on annuities in the post linked below if you are interested.

https://www.shrewdm.com/MB?pid...

Jeff