The conventional view of delaying Social Security is that doing so is an opportunity to earn delayed retirement credits, an 8%/year increase in benefits that can be highly appealing in today’s low-yield environment.
However, the reality is that delaying Social Security benefits doesn't just increase benefits by earning delayed retirement credits. Additional years of working while collecting Social Security benefits can also increase the worker’s Average Indexed Monthly Earnings used to calculate those Social Security benefits in the first place, just as ending work early can reduce AIME below what is projected as benefits on the Social Security statement.
And depending on how much additional income will be earned – and how low his/her historical earnings really are – the reality is that continuing to work while getting Social Security benefits can produce a material increase in future payments for some workers, simply because of how benefits are recalculated. In other words, for those past full retirement age (and no longer subject to the Earnings Test), it’s possible to be receiving Social Security benefits while working and have those years added to the Social Security work history to generate higher future benefits as well!
In the end, working while on Social Security won’t always produce a significant increase in Social Security benefits. For those whose prior working years produced more income – at least on an inflation-adjusted basis – it’s possible that continuing to work will generate no additional benefits at all. Nonetheless, for those who haven’t fully capped out Social Security benefits based on 35 years of maximal earnings already, it is possible to be working and getting Social Security benefits at the same time, and have that work increase the benefits (at least after reaching full retirement age). And the potential for a benefits increase can be material in some cases, and thus should definitely be considered in the timing and impact of when to stop working!