Both my local leagues have had a deadline in our league bylaws for decades.
All league fees owed are due by kickoff of the Superbowl.
Once all league fees are collected then checks/PayPal/cash go out to the winners however they desire to get their winnings.
So you may ask, why are league fees owed after the season? Well, the actual yearly team fee is paid at the draft (you are kicked out if you don't pay).
We charge $$ per transaction, charge per lowest weekly score (as well as payout high score) and so forth.
So once the season is over after week 16 champtionships, within a couple days I do a full accounting balance with what is owed and what people won. Then I contact those that owe on paying up.
I typically have everything collected by the week before the Superbowl and start paying those that won moola. If I will run into them at a SuperBowl party I'll give them a check there unless they requested it earlier.
If you don't pay what you owe by the SuperBowl or have made arrangements with the commish, you're kicked out. That simple.