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 points 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.

{
 "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
   }
 ]
}

When Using Custom Fields

The use of custom Fields is explain on the page : ..

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"
   }
   }
 ]
}