Late Payments: Interest fees, Handling fees, Collection Costs, Service fees

[ACEsterhuizen]

Can someone special please advise me on what fees (on top of the invoice amount) i can charge on outstanding invoices (30 days and more).

At the moment I charge 2% interest fee Incidental credit agreement as per the credit act. I add another 4% Administration Charges and 4% Collection Costs. This adds up to 10% per month (i know ) for non-paid invoices and it accumulates monthly.

Can I do this or is it illegal?

Thanks in advance.