The issued document reflects the value of the goods provided by the entity free of charge to a buyer/traveler not residing within the Community (EU) and departing for a third country from Greece.
The object “vatMediator” is mandatory for tax-free invoices, as it returns the VAT amount to the counterparty. The object includes information about the name of the mediator, VAT, and address details.
Extra mandatory strings in order the counterparty to receive the tax refund, are Identity or passport number and Issuance Country Code

json definition with remarks:

{
    "Currency": "Euro",
    "CurrencyCode": "EUR",
    "InvoiceType": "TAX FREE INVOICE",
    "InvoiceTypeCode": "11.1",
    "DocumentTypeCode": "INVOICE",
    "Series": "TAXFREE",
    "Number": "10",
    "DateIssued": "2024-02-22",
    "SpecialInvoiceCategory": 4, //mandatory declares that it concerns a Tax Free Document
    "CorrelatedInvoices": [],
    "issuer": {
        "registeredName": "Happy Shopping",
        "registrationNumber": "118058830",
        "vat": "EL123456789",
        "taxOffice": "ΦΑΕ ΑΘΗΝΩΝ",
        "activities": [],
        "generalCommercialRegistryNumber": "Γ.Ε.Μ.Η.",
        "phones": [
            "2109999999"
        ],
        "faxes": [],
        "emails": [],
        "address": {
            "countryCode": "GR",
            "municipality": "Athens",
            "city": "Athens",
            "street": "Κηφισού",
            "number": "32",
            "postal": "11000"
        }
    },
    "CounterParty": {
        "RegisteredName": "Chinese Tourist",
        "Vat": "CN155878685",
        "IdentityIdentifier": "AOT383", // mandatory - Identity or Passport number
        "IdentityIssuanceCountryCode": "CN", //mandatory - country of issue of identity/passport 
        "Address": {
            "CountryCode": "CN",
            "City": "Beijing",
            "Street": "Muxing Rd",
            "number": "59",
            "Postal": "100038"
        }
    },
    "vatMediator": { //mandatory for taxFree invoices, vatMediator returns the vat amount to the counterparty
        "RegisteredName": "vatMediator Name",
        "Vat": "EL123456789",
        "Address": {
            "CountryCode": "GR",
            "City": "Athens",
            "Street": "Lekka",
            "number": "51",
            "Postal": "10562"
        }
    },
    "DistributionDetails": {
        "InternalDocumentId": "TESTTAXFREE10"
    },
    "PaymentDetails": {
        "PaymentMethods": [
            {
                "PaymentMethodType": "cash",
                "PaymentMethodTypeCode": 3,
                "Amount": 100
            }
        ],
        "PaymentDate": "2024-02-22T08:11:48.413+00:00"
    },
    "AdditionalDetails": {
        "AccountingDepartmentEmails": [
            "test@sample.gr"
        ],
        "TransmissionMethod": "A"
    },
    "Details": [
        {
            "LineNo": 1,
            "Code": "10001826",
            "Descriptions": [
                "Τουριστικο δειγμα ακροπολης" // mandatory the description of the product
            ],
            "MeasurementUnit": "TMX",
            "MeasurementUnitCode": 1,
            "Quantity": 1,
            "CatalogUnitPrice": 100,
            "CatalogNetTotal": 100,
            "NetTotal": 100,
            "Total": 124,
            "VATTotal": 24.00,
            "VatCategory": "ΦΠΑ 24%",
            "VatCategoryCode": 1,
            "IsInformative": false,
            "RecordTypeCode": 0,
            "IncomeClassification": {
                "Id": 0,
                "ClassificationTypeCode": "E3_561_006",
                "ClassificationCategoryCode": "category1_1",
                "Amount": 100
            }
        }
    ],
    "Summaries": {
        "TotalNetAmount": 100,
        "TotalVATAmount": 24,
        "TotalGrossValue": 124,
        "TotalAllowances": 0
    },
    "isRetail": "true",
    "isDelayedCode": 0
}

Important remarks

• SpecialInvoiceCategory: The value 4 indicates that the document issued is a Tax Free document
• Issuer: Τhe details of the issuer are entered in this object and it is mandatory for all the invoices
  
• Counterparty: Τhe details of the counterparty are entered in this object. This is a mandatory field for the B2C documents
  
• IdentityIdentifier: This field is the identity or passport number and it is mandatory for tax free documents
  
• IdentityIssuanceCountryCode: This field is the country where the identity/passport of the counterparty has been issued
  
• VatMediator: The field includes information about the company that is obligated to refund VAT to the final customer.
• InternalDocumentId: It is a unique document number in the issuer’s system
  
• PaymethodTypeCode: This code corresponds to the paragraph 8.12 of IAPR myDATA documentation
  
• TransmissionMethod: If this field has value “E”, an email with the invoice url will be sent to the email address that has being setted to the field “AccountingDepartmentEmails”. If it has value “A”, the invoice is only going to be archived
  
• Details: In this object, each line is a product/service that you sell and all the details of it
  
• Summaries: the summary ammounts
  
• VatAnalysis: The analysis of vat amounts by percentage
  
• IsDelayedCode: This field is used for heterochronous transmission. Value 0: Realtime, 1: Problem on the issuer side, 2: Problem on the AADE side