PSA: I added a $50 late fee after day 14 and got paid in 3 days from a Denver client who owed me $1,800 | Empty Invoice Freakout - Freelance Forum - The Community for Independent Professionals
14 days feels tight to me since a lot of my clients run net 30 and that's just how their billing cycles work. If I slapped a $50 fee on day 15 I'd probably just annoy the ones who always pay, just a little later.