22 May Installment Payments
Usually in the invoice i give the possibilities to the clients to pay in more steps.
I use installment payments collecting the total paid in small parts in a fixed period of time .
For example 20% at the sign, then 40% after 90 days, and 40% after 180 days with number of installments, percentage and number of days variables.
I suggest this feature and to add in a a calendar with all the expiring date showed and maybe a system to send remainder to the client.