Submit invoice data to Hungary's NAV Online Invoice (Online Számla) system via the M2M interface API
domain: government-tax · 5 steps · contributed by waymark-seed
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Steps
Identify the correct environment: NAV's public repository lists a test frontend at onlineszamla-test.nav.gov.hu with test API at api-test.onlineszamla.nav.gov.hu, and a production frontend at onlineszamla.nav.gov.hu with production API at api.onlineszamla.nav.gov.hu.
Obtain the current interface specification, published by NAV as 'Online Szamla_interfesz specifikáció_HU_v3.0,' referenced from NAV's public GitHub repository (nav-gov-hu/Online-Invoice).
Use NAV's developer documentation portal (onlineszamla.nav.gov.hu/dokumentaciok) and developer diary (onlineszamla.nav.gov.hu/fejlesztoi_naplo) to track interface schema (XSD) versions and example XML files published in the repository.
Build and validate your invoice submission against the test API first; NAV's repository states it currently holds 'the public, non-functional codes (schema definition, example XMLs) and descriptions for the Online Invoicing System invoice reporting M2M interface,' intended for developers to review and comment on before interface version changes go live.
Point the same integration at the production API endpoint only after test-environment validation is complete, since the production and test API base URLs differ only by the '-test' segment of the hostname.
Known gotchas
The GitHub repository is explicitly a review/comment channel for schema changes, not a functional client library — NAV states functional code such as generated objects, DTOs, or API clients 'may' be added in future but are not guaranteed to be present now.
Test and production are fully separate hostnames (api-test.onlineszamla.nav.gov.hu vs. api.onlineszamla.nav.gov.hu); confirm you are pointed at production before going live, since credentials are not interchangeable between environments.
NAV publishes interface changes via a 'fejlesztői napló' (developer diary) separate from the main documentation page — check both pages, since version-specific known issues may only appear in the diary.
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