Is it a mortal sin to officate youth "CYO" basketball on Sunday? I can't find a job and I need the money. Technically, I am an independent contractor so I pick and choose what games I do. Am I committing mortal sin by deliberate accepting Sunday games when I don't have to? Could the mortal sin be reduced to venial sin because I don't have a regular job yet?
You're working on Sunday. What don't you understand?
Other than by working in certain important professions, there isn't an exception. Especially for sports.
If you live under your parents, why do you need money? Is the few bucks you make on Sunday worth offending God and burning in Hell for an eternity?
If people who work on Sunday under threat of termination are committing sin, it's egregious that you yourself are freely
choosing to work on Sunday.
Remember what Christ said: that "the love of money is the root of all evil".