NAV Online Számla XML 3.0: Technical Requirements & Data Fields

Hungary's NAV Online Számla XML 3.0 schema requires detailed line-item level reporting for all invoices, with over 80 data fields covering header, line, and summary sections. The schema is stricter than many EU counterparts — it requires individual product descriptions, unit prices, and ÁFA amounts per line item, not just invoice totals.

What Is the NAV XML 3.0 Schema?

NAV XML 3.0 (invoiceData v3.0) is the mandatory data format for reporting invoice data to Hungary's NAV Online Számla system. Published by NAV at onlineszamla.nav.gov.hu, the schema defines the complete structure for invoice submission via the REST API.

Schema Structure

• invoiceExchange: Root element containing the submission metadata
• invoiceHead: Supplier and customer data, invoice category, payment method
• invoiceLines: Individual line items with product data, quantities, prices, and ÁFA breakdown
• invoiceSummary: Aggregated totals per ÁFA rate category

Mandatory Fields — Header (invoiceHead)

Mandatory Fields — Header (invoiceHead) includes: supplierInfo: Tax number (adószám), name, address — validated against NAV registry customerInfo: Tax number (if B2B), name, address

• supplierInfo: Tax number (adószám), name, address — validated against NAV registry
• customerInfo: Tax number (if B2B), name, address
• invoiceNumber: Unique sequential number
• invoiceIssueDate: Date of issue (YYYY-MM-DD)
• invoiceCategory: NORMAL, SIMPLIFIED, or AGGREGATE
• paymentMethod: TRANSFER, CASH, CARD, VOUCHER, OTHER
• currencyCode: HUF or foreign currency with exchange rate

Mandatory Fields — Lines (invoiceLines)

Mandatory Fields — Lines (invoiceLines) includes: lineDescription: Product or service description quantity: Number of units

Each line item requires:

• lineDescription: Product or service description
• quantity: Number of units
• unitOfMeasure: Unit code from NAV's unit catalog
• unitPrice: Price per unit excluding ÁFA
• lineNetAmount: Net amount (quantity × unit price)
• lineVatRate: ÁFA rate (27%, 18%, 5%, or exempt)
• lineVatAmount: Calculated ÁFA for this line
• lineGrossAmount: Gross amount including ÁFA

Common Validation Errors

Common Validation Errors — TAXNUM_INVALID: Supplier or customer tax number format incorrect — Use 8-digit adószám format: XXXXXXXX-Y-ZZ.

Error Code	Description	Fix
TAXNUM_INVALID	Supplier or customer tax number format incorrect	Use 8-digit adószám format: XXXXXXXX-Y-ZZ
SCHEMA_VIOLATION	XML doesn't conform to XSD	Validate against NAV's published v3.0 XSD
LINE_CALC_ERROR	Line amounts don't match (qty × price ≠ net amount)	Verify arithmetic with HUF rounding rules
SUMMARY_MISMATCH	Summary totals don't match line item aggregation	Recalculate summaries from line data
DUPLICATE_INVOICE	Invoice number already reported	Ensure unique numbering per tax year

API Authentication

API Authentication includes: Technical user credentials: Login/password pair created on the NAV portal Request signature: HMAC-SHA512 hash of request data using the signature key

NAV API uses a two-layer authentication:

1. Technical user credentials: Login/password pair created on the NAV portal
2. Request signature: HMAC-SHA512 hash of request data using the signature key
3. Exchange key: AES-128 encryption key for sensitive data

How Invoicemonk Handles NAV XML 3.0

Invoicemonk automatically generates NAV XML 3.0 from invoice data, handles API authentication, and submits in real-time. Our compliance engine validates all fields and arithmetic before submission, preventing the most common rejection errors.