@brucanna I might left out why Lubos programmed it that way. Any good reason, why?
A bit awkward where the Sales Invoice Define the Due Date where I did not explicitly mentioned it to the clients nor the need to force the due date mentioned in sales invoice.
Yes. The program relies on the due date for many features, including aging reports, status displays, list sorting, etc. And from an accounting perspective, every invoice is due at some point or you would not issue it.