I would appreciate the possibility of having an early and late payment auto-calculation for invoices. This would either give a discount on early payments of invoices before the due date or would start calculating late payment interest on overdue invoices.
I too would appreciate this - I manually offer early payment incentive for one customer by adding a note with a promised discount then editing the invoice if the lower payment is made (on time). This solved them continually paying late. I'd like to do more incentivising - and penalising for lateness! An automated option would be fantastic - and would help solve a problem faced by a lot of small businesses, i.e. how to get customers to pay on time!