User wants to create an invoice for interest adjustment. Is it possible to create an invoice where user can enter the amount manually?
Yes, you can create a manual invoice if you want to just create an invoice of any amount without linking unbilled time and expenses to it. You need to choose the Manual Invoice option under Billing > Invoices > Create New. Keep in mind that you will have to select a project to bill against. Check CORE Help Center for details on manual invoices.