Sending a Credit Note

The API body for Credit Note is similar to an invoice. Below some specific points of attention.

How to Define it is a Credit Note

When OrderType is set to CreditNote, the document will be defined as a CreditNote. The amounts stay positive.

{
 "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": 2,
   "UnitPriceExcl": 3.75,
   "Description": "Sticks",
   "VATPercentage": 21
   }
 ]
}

ExpiryDate remains a mandatory field.

Reference to an Invoice

When a CreditNote refers to a preceding Invoice, then this reference can be included. "AboutInvoiceNumber" is the tag used for it.

Specific point of attention:

if there is no link with an invoice, do not include the tag "AboutInvoiceNumber".
When using "AboutInvoiceNumber"
- Billit will check that the invoice number exists at Billit. If not, an error will be prompted.
- When you start with the creation of invoices via an API, the following scenario might occur:
  - Create a credit note via API with AboutInvoiceNumber,
  - The previous invoice was not created via Billit with API (was before the start with Billit)
  - Error will be prompted that invoice could not be found
  - Solution:
    - Send CreditNote via API without the field "AboutInvoiceNumber"
    - Create the Invoice in Billit (without sending, via API or manually), then create the CreditNote (via API or manually.

When Using Custom Fields

Specific to CreditNotes, the name the be use should contain "CreditNote" and not "Invoice". Below an example with a custom field on the second detail line:

{
 "OrderType": "CreditNote",
 "OrderDirection": "Income",
 "OrderNumber": "QS-9424",
 "OrderDate": "2025-06-15",
 "ExpiryDate": "2025-08-30",
 "AboutInvoiceNumber": "QS-9116",
  "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": 2,
   "UnitPriceExcl": 3.75,
   "Description": "Sticks",
      "VATPercentage": 21,   
   "CustomFields": {
   "CreditNoteLine.Note": "Your ref: TW-169944  Our ref: 25001377"
   }
   }
 ]
}