Send an invoice

Choose how to send your documents

1. The destination format (KSeF FA(3)), through the country's invoicing API.
2. The A-Cube standard CSV or UBL, through SFTP or the file upload API using A-Cube Transfer. Transfer converts your files to KSeF FA(3).
3. Your own format, the files your ERP already exports, with A-Cube Transfer. A-Cube builds the conversion to KSeF FA(3) during onboarding.

Ask A-Cube to activate A-Cube Transfer and confirm your format and file upload API access for this destination before the first upload.

Every invoice has a status property that describes the current stage of its life cycle.

A-Cube accepts an invoice only if it has been properly validated against the KSeF FA (3) Schema and additional business logic layer. If it's not valid, there is instant information provided with detailed information about the error. After successful validation, the invoice is stored in A-Cube's secure space and forwarded to KSeF.

The invoice with in_queue status will be sent to KSeF in hourly intervals.

There are a few fields that are related to KSeF processing:

"ksefReferenceNumber": "8431324763-20221010-C2EE39-1AC5D0-06", - Special Number assigned by KSeF
"acquisitionTimestamp": "2022-10-10 12:53:32" - Acquisition time at KSeF

Sample Invoice upload

POST /invoices/v3

{
  "Naglowek": {
    "KodFormularza": {
      "__value": "FA",
      "kodSystemowy": "FA (3)",
      "wersjaSchemy": "1-0E"
    },
    "WariantFormularza": "3",
    "DataWytworzeniaFa": "2025-09-14T12:46:25+00:00"
  },
  "Podmiot1": {
    "DaneIdentyfikacyjne": {
      "NIP": "9999999999",
      "Nazwa": "Sender"
    },
    "Adres": {
      "KodKraju": "PL",
      "AdresL1": "Testowa"
    },
    "Telefon": []
  },
  "Podmiot2": {
    "DaneIdentyfikacyjne": {
      "BrakID": "1"
    },
    "JST": "2",
    "GV": "2",
    "Adres": {
      "KodKraju": "PL",
      "AdresL1": "Testowa"
    },
    "Telefon": []
  },
  "Podmiot3": [],
  "Fa": {
    "KodWaluty": "PLN",
    "P_1": "2022-01-01",
    "P_2": "FV\/2025\/09\/14\/12\/46\/25",
    "WZ": [],
    "P_13_1": 7700.0,
    "P_14_1": 2300.0,
    "P_15": 10000.0,
    "Adnotacje": {
      "P_16": "2",
      "P_17": "1",
      "P_18": "2",
      "P_18A": "2",
      "Zwolnienie": {
        "P_19N": "1"
      },
      "NoweSrodkiTransportu": {
        "NowySrodekTransportu": [],
        "P_22N": "1"
      },
      "P_23": "1",
      "PMarzy": {
        "P_PMarzyN": "1"
      }
    },
    "RodzajFaktury": "VAT",
    "DaneFaKorygowanej": [],
    "DaneFaKorygowanejPozaKSEF": [],
    "Podmiot2K": [],
    "P_6Z": [],
    "P_15Z": [],
    "KursWalutyZW": [],
    "DodatkowyOpis": [],
    "NrFaZaliczkowej": [],
    "FaWiersz": []
  }
}

cURL Example of invoice sending as raw XML

curl --location --request POST 'https://pl-sandbox.api.acubeapi.com/invoices/v3' \
--header 'Authorization: Bearer $Token' \
--header 'Content-Type: application/xml' \
--data-raw '$XML_CONTENT'