Payment Interest

I have only just started testing Manager for my small furniture business. It seems to be able to do everything I need. The only stopper for me is that I take in payments on furniture from my customers, I have figured out how to show incoming payments, but I also charge a interest fee and don’t see how to do that. What I would like is to be able to input an interest amount and be able to code in for the customers that I am charging. Any help with this would be greatly appreciated. Thx.

Please are you talking about late payment fee?

Is the interest fee - fixed (one off charge) or variable (changes with time)
Could you expand upon your actual steps a little more fully
Under Setting - Sales Invoice Items , you could set up an item as “Interest Fee” with a nominated income account. Then during the creation of the customers invoice that item becomes selectable

Your idea will work for me and turned on a light for me. Thanks for your input.