"The numbers in Kelly’s contract are manipulated, because as a private school, Notre Dame does not want a paper trail that shows a football coach among the highest paid employees.
As in past years, Notre Dame's federal tax return notes that Kelly is permitted to receive compensation from sources outside the university "with prior written approval from the university" and that any such income is not reported on the return.
When Charlie Weis was fired after the 2009 season, he told the South Bend Tribune that a significant amount of his compensation came through adidas, and another large portion from Notre Dame Sports Properties, for his radio and TV shows. It is very likely that Kelly’s deal with Notre Dame includes similar clauses."
Link: https://notredame.rivals.com/news/michigan-s-harbaugh-making-9m-per-season