Negative Lines on an Invoice

An invoice related to sales operations has a positive total. But it is allowed that one or more lines of the invoice has a negative Line Total.

How this is done in Billit:

Quantity is positive
UnitPriceExcl is negative.

This will be converted in e-invoice networks (e.g. Peppol) in the correct way.

Example of a Json body of an Invoice, where line one has negative total and line 2 has a positive total.

{
 "OrderType": "CreditNote",
 "OrderDirection": "Income",
 "OrderNumber": "QS-8596",
 "OrderDate": "2025-06-01",
 "ExpiryDate": "2025-08-30",
  "Customer": {
   "Name": "Billit",
   "VATNumber": "BE0563846944",
   "PartyType": "Customer",
   "Addresses": [
        {
        "AddressType": "InvoiceAddress",
        "Name": "Billit",
        "Street": "Oktrooiplein",
        "StreetNumber": "1",
        "City": "Ghent",
        "Box": "301",
        "CountryCode": "BE"
        }  
   ]
   },
 "OrderLines": [
  {
   "Quantity": 1,
   "UnitPriceExcl": -10.0,
   "Description": "Box of cookies",
   "VATPercentage": 6
   },
    {
   "Quantity": 4,
   "UnitPriceExcl": 3.75,
   "Description": "Sticks",
   "VATPercentage": 21
   }
 ]
}