Account for the Windfall Elimination Provision

[Gregable]

From @MikePiper:

As far as I can tell, SocialSecurity.tools doesn't have a way to account for the Windfall Elimination Provision (which applies when a person has a pension from work that wasn't covered by Social Security tax) when calculating a person's PIA.

The rules aren't terribly complicated. Basically, before applying the PIA formula (i.e., 90% of X, plus 32% of Y, plus 15% of Z) you count how many years of Social-Security-covered "substantial earnings" they've had. Then, the 90% figure in the PIA formula gets replaced with a different figure.
If you have 20 or fewer years with substantial earnings, the figure used will be 40% instead of 90%.
For each year of substantial earnings beyond 20, the figure increases by 5% (until you reach the original 90% figure).
The year-by-year thresholds for substantial earnings can be found here:
https://www.ssa.gov/pubs/EN-05-10045.pdf

But then there's one catch: The WEP will never reduce your PIA by more than 50% of your monthly pension from non-covered work.