E-invoicing in Hungary: A Complete Guide for Businesses

What is Hungary e-invoicing?

Hungary's Online Számla (Online Invoice) system, operated by NAV (Nemzeti Adó- és Vámhivatal — National Tax and Customs Administration), is one of the earliest mandatory real-time invoice reporting systems in Europe. Introduced under the VAT Act amendment in 2018, the system requires businesses to report invoice data to NAV's central server in real time or near-real time — within 24 hours of the invoice being issued for most transactions, and effectively immediately for invoices above the VAT threshold.

Unlike Italy's SDI, Online Számla is a reporting model, not a clearance model — invoices do not need NAV approval before they are sent to the buyer. However, the invoice data must be transmitted to NAV independently of the physical or electronic delivery to the customer.

The reporting obligation has expanded significantly since its launch:

• From 1 July 2018: mandatory for B2B invoices with VAT content exceeding HUF 100,000
• From 1 January 2021: mandatory for all domestic B2B invoices, including zero-VAT and EU intra-community invoices
• From 1 April 2021: mandatory for all VAT-registered entities (including businesses below the VAT threshold using the "alanyi mentes" exemption)

The NAV Online Számla format

Online Számla uses NAV's proprietary XML schema, currently version 3.0. Key technical characteristics:

• Schema: Online Számla XML Schema 3.0 (invoiceData namespace)
• API version: Online Számla API 3.0 (/manageInvoice, /queryInvoiceData endpoints)
• Authentication: technical user credentials (technicalUser) with NAV-generated XML signature using SHA-512; each API call is signed
• Invoice data hash: the invoiceData element contains a Base64-encoded compressed XML; the envelope contains an SHA-512 hash for integrity verification
• Fields: Hungarian tax number (adószám, format: XXXXXXXX-Y-ZZ) for supplier and buyer, invoice number, issue date, fulfillment date (teljesítési dátum), payment method, line items with VAT summary
• VAT rates: standard 27% (one of the highest in the EU), reduced 18% (food staples), 5% (medicines, books), 0% (intra-EU, export)
• Modification and cancellation: modifications (modificationIndex) and cancellations reference the original invoice by number and must be reported separately

Who does it apply to?

Foreign businesses with Hungarian VAT registrations are subject to the full Online Számla obligation.

Timeline / key dates

• 1 Jul 2018: Real-time reporting mandatory for B2B invoices with >HUF 100K VAT
• 1 Jan 2020: Threshold lowered; near-real-time reporting tightened
• 1 Jan 2021: All B2B domestic invoices and intra-EU transactions mandatory
• 1 Apr 2021: All VAT-registered businesses, regardless of turnover
• Ongoing: NAV maintains the schema at v3.0; future schema versions communicated in advance

How Clearvo handles Hungary e-invoicing

Clearvo generates the Online Számla 3.0 XML payload, handles the NAV cryptographic signing (SHA-512, Base64 compression), submits to the NAV API, and returns the NAV transaction ID confirming receipt.

Key points:

• NAV technical user credentials are configured once in Clearvo; all subsequent invoice reports use these credentials
• The teljesítési dátum (fulfillment date) is distinct from the issue date — Clearvo maps this from serviceDate in your payload or defaults to the issue date
• Invoice modifications and cancellations are handled via the modificationIndex field in the API
• Clearvo retries on NAV connectivity failures and stores the transaction ID per invoice

What you send: standard invoice fields plus supplierAdoszam, customerAdoszam, fulfillmentDate, and buyerCountry: "HU".

What you get back: NAV transaction ID (transactionId), processing status, and the submitted XML.

{
  "invoiceNumber": "SZL-2025-00089",
  "issueDate": "2025-03-01",
  "fulfillmentDate": "2025-02-28",
  "dueDate": "2025-03-31",
  "currency": "HUF",
  "supplier": {
    "name": "Acme Software Kft.",
    "vatNumber": "HU12345678",
    "adoszam": "12345678-2-41",
    "address": {
      "street": "Andrássy út 22",
      "city": "Budapest",
      "postalCode": "1061",
      "country": "HU"
    }
  },
  "customer": {
    "name": "Magyar Tech Zrt.",
    "vatNumber": "HU87654321",
    "adoszam": "87654321-2-44",
    "address": {
      "street": "Váci út 15",
      "city": "Budapest",
      "postalCode": "1133",
      "country": "HU"
    }
  },
  "lines": [
    {
      "description": "Szoftverlicenc — 2025. február",
      "quantity": 1,
      "unitPrice": 750000,
      "taxRate": 27,
      "taxCategory": "S"
    }
  ],
  "paymentMethod": "TRANSFER",
  "bankAccount": {
    "iban": "HU42117730161111101800000000"
  }
}

Getting started

Online Számla 3.0 API authentication, XML schema documentation, and transaction ID polling are at clearvo.io/docs. NAV provides a test environment at api-test.onlineszamla.nav.gov.hu; use environment: "sandbox" in Clearvo to target it.

Related country guides

• Poland — KSeF clearance model, mandatory from February 2026
• Romania — RO e-Factura clearance, mandatory since 2024
• Slovakia — Peppol BIS 3.0, B2B mandate roadmap