When creating orders it is possible to add a ventilation code to the invoice. These codes represents VAT information. Information below is elaborated when sending is to TransferType Peppol.

Income / Sales Invoices

There is no need to include a ventillation code in the API JSON Body:

When tax % greater than zero (Ventillation Code is 2, 3, 4 , ...)
When tax % is 0, and no specific code or exemption reason is need. Peppol TaxcategoryID will be Z and Tax exemption reason will be empty.

When Tax includes lines of 0 % and Specific codes and exemption reasons are needed, then a specific ventilation code must be included. This applies to the Peppol Taxcategory ID AE, E, K, G. More info about the meaning : Peppol CodeList.

Below the overview for Sales Invoices:

Billit Ventilation Code	Description Ventilation Code	Default Vat %	Peppol UBL TaxCategory ID	TaxExemptionReason Text in Peppol UBL
1	0%	0.00	Z	-
2	6%	6.00	S	-
3	12%	12.00	S	-
4	21%	21.00	S	-
21	BTW Verlegd (VAT shifted, VAT Reverse charges)	0.00	AE	Reverse Charge
22	Div. Buiten BTW (Misc. Excluding VAT)	0.00	E	Exempt from VAT
24	Marge (Margin)	0.00	E	Exempt from VAT
51	IC Goederen (IC Goods)	0.00	K	VAT exempt for EEA intra-community supply of goods and services
55	IC Diensten (IC Services)	0.00	K	VAT exempt for EEA intra-community supply of goods and services
70	Import / Export	0.00	G	Free export item, VAT not charged

How to use it practically:

Ventilation code is included on header level (no need to include it on line level)
Ventilation code is only needed when Taxcategory ID AE, E, K or G is used
Per invoice, only 1 Ventillation Code is mentioned

Below an Example :

scenario
- line 1 and 2 have VAT % 0 (goal is Taxcategory ID = K)
- line 3 VAT % 21 (goal is Taxcategory ID = S)
Ventilation code
- One ventilation code 55 is put on header level in order to get Taxcategory ID K
- Peppol UBL File
  - Subtotals: TaxcategoryID K and TaxExemption Reason are present:
  - Detail line : ClassifiedTaxCategory is set to K for lines with 0 %:

Below the example files:
- Json Body with ventillation code 55
- Peppol UBL with TaxCategoryID K

{
    "OrderNumber": "month-41.100-5",
    "OrderTitle": "FC24000230",
    "VentilationCode": "55", //Ventilation code is defined IC Diensten (IC Services), will be used for all lines with VATpercentage 0 %. ), Result Peppol code is K.
    "Currency": "EUR",
    "PaymentTerms": "30 days",
    "Customer": {
        "Name": "TestCustomer",
        "CommercialName": "TestCustomer",
        "Addresses": [
            {
                "AddressType": "InvoiceAddress",
                "Street": "Oktrooiplein 1",
                "Box": "Building B",
                "Zipcode": "9000",
                "City": "Gent",
                "CountryCode": "BE"
            },
        ],
        "Contact": "Jean Delveaux",
        "VATNumber": "BE0437295202",
        "PartyType": "Customer",
        "VATLiable": true,
        "VATDeductable": true,
        "Identifiers": [
        ],
    },
    "OrderDate": "2025-05-05T11:25:00.4667841+02:00",
    "ExpiryDate": "2025-06-04T11:25:00.466804+02:00",
    "OrderType": "Invoice",
    "OrderDirection": "Income",
    "OrderLines": [
        {
            "Quantity": 1.0,
            "UnitPriceExcl": 50.0,
            "Reference": "Line.1.Reference",
            "Description": "0/63 TDLSF",
            "VATPercentage": 0.0,
            "DescriptionExtended": "0/63 TDLSF Extended"
        },
        {
            "Quantity": 1.0,
            "UnitPriceExcl": 50.0,
            "Reference": "Line.2.Reference",
            "Description": "0/63 TDLSF",
            "VATPercentage": 0.0,
            "DescriptionExtended": "0/64 TDLSF Extended"
        },
            {
            "Quantity": 2.0,
            "UnitPriceExcl": 4.0,
            "Reference": "Line.1.Reference",
            "Description": "0/63 TDLSF",
            "VATPercentage": 21.0,
            "DescriptionExtended": "0/63 TDLSF Extended"
        },
    ],
}

<?xml version="1.0"?>
<Invoice xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2" xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2" xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2">
  <cbc:CustomizationID>urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0</cbc:CustomizationID>
  <cbc:ProfileID>urn:fdc:peppol.eu:2017:poacc:billing:01:1.0</cbc:ProfileID>
  <cbc:ID>month-41.100-15</cbc:ID>
  <cbc:IssueDate>2025-05-05</cbc:IssueDate>
  <cbc:DueDate>2025-06-04</cbc:DueDate>
  <cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
  <cbc:DocumentCurrencyCode>EUR</cbc:DocumentCurrencyCode>
  <cbc:BuyerReference>FC24000230</cbc:BuyerReference>
  <cac:OrderReference>
    <cbc:ID>FC24000230</cbc:ID>
  </cac:OrderReference>
  <cac:AccountingSupplierParty>
    <cac:Party>
      <cbc:EndpointID schemeID="0208">0759529999</cbc:EndpointID>
      <cac:PartyIdentification>
        <cbc:ID schemeID="0208">0759529999</cbc:ID>
      </cac:PartyIdentification>
      <cac:PartyName>
        <cbc:Name>Testsupplier</cbc:Name>
      </cac:PartyName>
      <cac:PostalAddress>
        <cbc:StreetName>straat 31</cbc:StreetName>
        <cbc:CityName>Gent</cbc:CityName>
        <cbc:PostalZone>9000</cbc:PostalZone>
        <cac:Country>
          <cbc:IdentificationCode>BE</cbc:IdentificationCode>
        </cac:Country>
      </cac:PostalAddress>
      <cac:PartyTaxScheme>
        <cbc:CompanyID>BE0759529999</cbc:CompanyID>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:PartyTaxScheme>
      <cac:PartyLegalEntity>
        <cbc:RegistrationName>npnwbrabant</cbc:RegistrationName>
        <cbc:CompanyID schemeID="0208">0759529999</cbc:CompanyID>
      </cac:PartyLegalEntity>
      <cac:Contact>
        <cbc:Name>Jan Janssens</cbc:Name>
        <cbc:Telephone>+32479999999</cbc:Telephone>
        <cbc:ElectronicMail>[email protected]</cbc:ElectronicMail>
      </cac:Contact>
    </cac:Party>
  </cac:AccountingSupplierParty>
  <cac:AccountingCustomerParty>
    <cac:Party>
      <cbc:EndpointID schemeID="0208">0437295999</cbc:EndpointID>
      <cac:PartyIdentification>
        <cbc:ID schemeID="0208">0437295999</cbc:ID>
      </cac:PartyIdentification>
      <cac:PartyName>
        <cbc:Name>TestCustomer</cbc:Name>
      </cac:PartyName>
      <cac:PostalAddress>
        <cbc:StreetName>Oktrooiplein 1  Building B</cbc:StreetName>
        <cbc:CityName>Gent</cbc:CityName>
        <cbc:PostalZone>9000</cbc:PostalZone>
        <cac:Country>
          <cbc:IdentificationCode>BE</cbc:IdentificationCode>
        </cac:Country>
      </cac:PostalAddress>
      <cac:PartyTaxScheme>
        <cbc:CompanyID>BE0437295202</cbc:CompanyID>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:PartyTaxScheme>
      <cac:PartyLegalEntity>
        <cbc:RegistrationName>TestCustomer</cbc:RegistrationName>
        <cbc:CompanyID schemeID="0208">0437295999</cbc:CompanyID>
      </cac:PartyLegalEntity>
      <cac:Contact>
        <cbc:Name>Jean Delveaux</cbc:Name>
      </cac:Contact>
    </cac:Party>
  </cac:AccountingCustomerParty>
  <cac:Delivery>
    <cac:DeliveryLocation>
      <cac:Address>
        <cac:Country>
          <cbc:IdentificationCode>BE</cbc:IdentificationCode>
        </cac:Country>
      </cac:Address>
    </cac:DeliveryLocation>
  </cac:Delivery>
  <cac:PaymentMeans>
    <cbc:PaymentMeansCode>42</cbc:PaymentMeansCode>
    <cbc:PaymentID>FC24000230</cbc:PaymentID>
    <cac:PayeeFinancialAccount>
      <cbc:ID>BE13523081289999</cbc:ID>
      <cac:FinancialInstitutionBranch>
        <cbc:ID>TRIOBEBB</cbc:ID>
      </cac:FinancialInstitutionBranch>
    </cac:PayeeFinancialAccount>
  </cac:PaymentMeans>
  <cac:TaxTotal>
    <cbc:TaxAmount currencyID="EUR">1.68</cbc:TaxAmount>
    <cac:TaxSubtotal>
      <cbc:TaxableAmount currencyID="EUR">100.00</cbc:TaxableAmount>
      <cbc:TaxAmount currencyID="EUR">0.00</cbc:TaxAmount>
      <cac:TaxCategory>
        <cbc:ID>K</cbc:ID>
        <cbc:Percent>0.00</cbc:Percent>
        <cbc:TaxExemptionReason>VAT exempt for EEA intra-community supply of goods and services</cbc:TaxExemptionReason>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:TaxCategory>
    </cac:TaxSubtotal>
    <cac:TaxSubtotal>
      <cbc:TaxableAmount currencyID="EUR">8.00</cbc:TaxableAmount>
      <cbc:TaxAmount currencyID="EUR">1.68</cbc:TaxAmount>
      <cac:TaxCategory>
        <cbc:ID>S</cbc:ID>
        <cbc:Percent>21.00</cbc:Percent>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:TaxCategory>
    </cac:TaxSubtotal>
  </cac:TaxTotal>
  <cac:LegalMonetaryTotal>
    <cbc:LineExtensionAmount currencyID="EUR">108.00</cbc:LineExtensionAmount>
    <cbc:TaxExclusiveAmount currencyID="EUR">108.00</cbc:TaxExclusiveAmount>
    <cbc:TaxInclusiveAmount currencyID="EUR">109.68</cbc:TaxInclusiveAmount>
    <cbc:AllowanceTotalAmount currencyID="EUR">0</cbc:AllowanceTotalAmount>
    <cbc:ChargeTotalAmount currencyID="EUR">0</cbc:ChargeTotalAmount>
    <cbc:PrepaidAmount currencyID="EUR">0.00</cbc:PrepaidAmount>
    <cbc:PayableAmount currencyID="EUR">109.68</cbc:PayableAmount>
  </cac:LegalMonetaryTotal>
  <cac:InvoiceLine>
    <cbc:ID>1</cbc:ID>
    <cbc:InvoicedQuantity unitCode="NAR">1.00000</cbc:InvoicedQuantity>
    <cbc:LineExtensionAmount currencyID="EUR">50.00</cbc:LineExtensionAmount>
    <cac:OrderLineReference>
      <cbc:LineID>Line.1.Reference</cbc:LineID>
    </cac:OrderLineReference>
    <cac:Item>
      <cbc:Description>0/63 TDLSF Extended</cbc:Description>
      <cbc:Name>0/63 TDLSF</cbc:Name>
      <cac:SellersItemIdentification>
        <cbc:ID>Line.1.Reference</cbc:ID>
      </cac:SellersItemIdentification>
      <cac:ClassifiedTaxCategory>
        <cbc:ID>K</cbc:ID>
        <cbc:Percent>0.00</cbc:Percent>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:ClassifiedTaxCategory>
    </cac:Item>
    <cac:Price>
      <cbc:PriceAmount currencyID="EUR">50.00000</cbc:PriceAmount>
      <cbc:BaseQuantity>1</cbc:BaseQuantity>
    </cac:Price>
  </cac:InvoiceLine>
  <cac:InvoiceLine>
    <cbc:ID>2</cbc:ID>
    <cbc:InvoicedQuantity unitCode="NAR">1.00000</cbc:InvoicedQuantity>
    <cbc:LineExtensionAmount currencyID="EUR">50.00</cbc:LineExtensionAmount>
    <cac:OrderLineReference>
      <cbc:LineID>Line.2.Reference</cbc:LineID>
    </cac:OrderLineReference>
    <cac:Item>
      <cbc:Description>0/64 TDLSF Extended</cbc:Description>
      <cbc:Name>0/63 TDLSF</cbc:Name>
      <cac:SellersItemIdentification>
        <cbc:ID>Line.2.Reference</cbc:ID>
      </cac:SellersItemIdentification>
      <cac:ClassifiedTaxCategory>
        <cbc:ID>K</cbc:ID>
        <cbc:Percent>0.00</cbc:Percent>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:ClassifiedTaxCategory>
    </cac:Item>
    <cac:Price>
      <cbc:PriceAmount currencyID="EUR">50.00000</cbc:PriceAmount>
      <cbc:BaseQuantity>1</cbc:BaseQuantity>
    </cac:Price>
  </cac:InvoiceLine>
  <cac:InvoiceLine>
    <cbc:ID>3</cbc:ID>
    <cbc:InvoicedQuantity unitCode="NAR">2.00000</cbc:InvoicedQuantity>
    <cbc:LineExtensionAmount currencyID="EUR">8.00</cbc:LineExtensionAmount>
    <cac:OrderLineReference>
      <cbc:LineID>Line.1.Reference</cbc:LineID>
    </cac:OrderLineReference>
    <cac:Item>
      <cbc:Description>0/63 TDLSF Extended</cbc:Description>
      <cbc:Name>0/63 TDLSF</cbc:Name>
      <cac:SellersItemIdentification>
        <cbc:ID>Line.1.Reference</cbc:ID>
      </cac:SellersItemIdentification>
      <cac:ClassifiedTaxCategory>
        <cbc:ID>S</cbc:ID>
        <cbc:Percent>21.00</cbc:Percent>
        <cac:TaxScheme>
          <cbc:ID>VAT</cbc:ID>
        </cac:TaxScheme>
      </cac:ClassifiedTaxCategory>
    </cac:Item>
    <cac:Price>
      <cbc:PriceAmount currencyID="EUR">4.00000</cbc:PriceAmount>
      <cbc:BaseQuantity>1</cbc:BaseQuantity>
    </cac:Price>
  </cac:InvoiceLine>
</Invoice>

Cost

Code	Description	Default Vat Amount
1	Binnenland (Inland)	NULL
21	BTW Verlegd (VAT shifted)	0.00
22	Div. Buiten BTW (Misc. Excluding VAT)	NULL
111	Marge (Margin)	0.00
51	IC Goederen (IC Goods)	0.00
55	IC Diensten (IC Services)	0.00
102	Import Via EU	NULL