[jyl]

Oof modeling one's SS benefit is complicated. I "think" it works like this - but still need to verify, might end up calling SSA.

1. take every year's SS taxable earnings during lifetime
2. compute "index factor" for each year (index factor = average national wage for your retirement year / average national wage for the year being computed)
3. multiply each year's SS taxable earnings by index factor to get "indexed earnings" (this is basically your SS taxed earnings for that year adjusted for wage inflation)
4. find the 35 years with the highest indexed earnings
5. sum the indexed earnings of those 35 years
6. divide by 420 to get "average indexed monthly earning" (AIME)
7. look up the "first bend point" and "second bend point" for your retirement year
8. calculate "primary insurance amount" (PIA) as 90% of the first bend point + 32% of AIME between first and second bend points + 15% of AIME above second bend point (basically, the SS benefit is designed to replace more of low AIME and less of high AIME)

Benefit is reduced if you retire before age 67 which hopefully won't apply to me. Benefit is increased if you retire later than age 67, by 8% per year, up to age 70. After you retire, benefits are adjusted by inflation-based cost of living adjustments ("COLA").

I am pretty sure (but since this is the key point, need to verify) that the PIA calculation is done as of your retirement date or age 70, whichever is earlier. Thus additional high-income years up to age 70 can potentially affect your PIA . . .

. . . or not, as I'm finding.

Basically, the AIME calculation uses only your 35 highest indexed earning years, so if you will have a long working history when you retire, say 50 years, then many or most or even all of your lowest indexed earning years will be excluded from the calculation. If you add some high indexed earnings years to the tail end of your earnings history, they do displace low indexed earnings years, but the lowest years were already excluded from AIME. With the cap on SS taxable earnings, the scope to affect your benefit is limited, maybe very limited.

As best I can tell, regardless of my future SS taxable earnings, my PIA assuming retirement at 70 can only change <$100/mo. KC, you won your bet.

All of these are based on assumptions for future inflation. Inflation changes the PIA quite a bit, but doesn't change the sensitivity of PIA to future earnings.

YMMV of course. If your top 35 indexed earnings years currently include many low indexed earnings years, then tacking on some high indexed earnings years to the end of your earnings history may have a larger effect.

P.S. if anyone's interested, I can clean up my spreadsheet calculating this, and share it.