User wants to set up project payment terms in a way that calculates the late fees from the due date onward, instead of calculating from the invoice date.
The payment terms in projects only determine the due date shown on the invoice. The interest determines the number of days the invoice is officially considered late, starting from the invoice date. When an invoice is considered late, the calculation goes all the way back to the invoice date, by design. To calculate late fees starting from the due date, you need to have a term of 0. This makes the invoice due upon receipt. You can set this term at the global level in Settings > Billing & Invoices > Accounts Receivable. You can also set this at the client or project level. Check CORE Help Center for details.