A theory that states that the term "due date" was meant to be "do date"; you do your work on that day. The definition was simply diluted over the years.
"Did you do your homework? It's due next week."
"No way brother I am a firm believer of the Due Date Theory. If it's due next week I'll do it next week."
Paying your cell phone/internet/cable when the service is threatened to be cut off, rather than the date due on the bill. This usually results in having to pay the bill in person with a money order because they don't have a checking account.
Klamydiah had to go down to Verizon to pay her phone bill. She stopped at Ray Ray's liquor and check cashing to get a money order cuz they gonna cut it off. I don't know why she wait till the section 8 due date.