Send the Invoice as a Model

var client = new RestClient("/einvoice/Send/Model");
client.Timeout = -1;
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("Accept", "text/plain");
request.AddHeader("Authorization", "Bearer <API KEY>");
var body = @"{
  "EInvoice": {
    "InvoiceInfo": {
      "UUID": "1f797839-fb10-45d3-818c-eaaeed533b76",
      "TemplateUUID": "28c9920d-c85d-4d07-a3a3-1b5a1d819949",
      "TemplateBase64String": null,
      "InvoiceType": "SATIS",
      "InvoiceSerieOrNumber": "EFT",
      "IssueDate": "2022-07-02T01:10:14.1406414+03:00",
      "CurrencyCode": "TRY",
      "ExchangeRate": null,
      "InvoiceProfile": "TICARIFATURA",
      "DespatchDocumentReference": null,
      "OrderReference": null,
      "OrderReferenceDocument": null,
      "AdditionalDocumentReferences": null,
      "TaxExemptionReasonInfo": null,
      "PaymentTermsInfo": null,
      "PaymentMeansInfo": null,
      "OKCInfo": null,
      "ReturnInvoiceInfo": null,
      "AccountingCost": null,
      "InvoicePeriod": null,
      "SGKInfo": null,
      "LineExtensionAmount": 0,
      "GeneralKDV1Total": 0,
      "GeneralKDV8Total": 0,
      "GeneralKDV18Total": 0,
      "GeneralAllowanceTotal": 0,
      "PayableAmount": 0,
      "KdvTotal": 0
    },
    "CompanyInfo": {
      "TaxNumber": "6310540565",
      "Name": "Nilvera Yazılım ve Bilişim Hiz. Tic. Ltd. Şti.",
      "TaxOffice": "Erciyes",
      "PartyIdentifications": null,
      "AgentPartyIdentifications": null,
      "Address": "Adres",
      "District": "Melikgazi",
      "City": "Kayseri",
      "Country": "Türkiye",
      "PostalCode": "38038",
      "Phone": "08502514010",
      "Fax": null,
      "Mail": "info@nilvera.com",
      "WebSite": "htts://nilvera.com"
    },
    "CustomerInfo": {
      "TaxNumber": "1234567801",
      "Name": "AAA Anonim Şirketi",
      "TaxOffice": null,
      "PartyIdentifications": null,
      "AgentPartyIdentifications": null,
      "Address": "Papatya Caddesi Yasemin Sokak No21",
      "District": "Melikgazi",
      "City": "Kayseri",
      "Country": "Türkiye",
      "PostalCode": "38038",
      "Phone": null,
      "Fax": null,
      "Mail": null,
      "WebSite": null
    },
    "BuyerCustomerInfo": null,
    "ExportCustomerInfo": null,
    "TaxFreeInfo": null,
    "InvoiceLines": [
      {
        "Index": null,
        "SellerCode": null,
        "BuyerCode": null,
        "Name": "Laptop",
        "Description": null,
        "Quantity": 1,
        "UnitType": "C62",
        "Price": 100,
        "AllowanceTotal": 0,
        "KDVPercent": 18,
        "KDVTotal": 0,
        "Taxes": null,
        "DeliveryInfo": null,
        "ManufacturerCode": null,
        "BrandName": null,
        "ModelName": null,
        "Note": null,
        "OzelMatrahReason": null,
        "OzelMatrahTotal": null
      }
    ],
    "Notes": [
      "Note 1",
      "Note 2"
    ]
  },
  "CustomerAlias": null
}";
request.AddParameter("application/json", body,  ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
Console.WriteLine(response.Content