RE: I don't see how this applies to SE tax

This was in my original post:

"Employment contract limits his moonlighting income.

In 2021, Employer exercises the claw-back provisions and claims $300K of back payment from TP for 2012 thru 2020. "     

Per the employment contract, when the moonlighting income exceeds certain level, he has to split the moonlighting income with the employer.   The claw-back was on the moonlighting income, i.e. the SE income. 

The employer did not dock the wages.  It was not like he lost money from the cash register...