The late interest will be charged when the payer fails to pay the invoice by the due date. This late interest can be set in the Late Charge Setting under Maintenance. As you can see under Invoice, there is a due date for every invoice issued. When the payer fails to pay on time, the payer will be charged the late interest rate that the user has set up in the settings.
For the calculation method used for late interest in the system, you may refer to this guideline
To see details of the invoice amount with the late interest charge:
Go to Transaction, Late Interest, Charge Late Interest.
Tick Generate Interest, Generate.
Go to Report, Transaction List, Billing Listing, and Late Charges List.
Click OK, Preview.