net 15 / net 30 and does anyone charge late fees

[kandalawncaremgr]

I'm curious on monthly billing contracts do you guys do net 15/30 also does anyone charge any late fees if payment isn't made. Last year I had three people that would wait 2 months to pay me. Its frustrating waiting around for money. So I was wondering if I applied a late fee maybe people would pay a little more attention. Any suggestions besides drop the people.