If I am continuing to work past 70 and am gaining additional years to offset my Windfall Elimination penalty, will my benefit continue to increase by holding off on filing? My Maximize My Social Security readout shows an increasing benefit after 70 which makes me believe that is possible.
Yes, if you continue working past age 70 and earn at least the amount required to be classified as 'substantial earnings' for purposes of the Windfall Elimination Provision (WEP), it could reduce the amount of WEP reduction applicable to your Social Security retirement benefit rate. At least, that is, assuming that you have between 20 and 30 substantial earnings years (https://www.ssa.gov/pubs/EN-05-10045.pdf). You don't need to hold off filing for benefits in order to receive the lesser reduction, though, and you wouldn't want to wait past age 70 to claim your Social Security retirement benefits because you no longer accrue delayed retirement credits (DRC) after age 70. The amount of your WEP reduction can be recalculated after any year in which you have substantial earnings.