NAV M2M: form filing and taxpayer queries

Kovács András · Content updated: 15 October 2026

Keep filing your forms after ÁNYK, over a machine connection and without IT expertise.

With SimplyX you file forms to NAV over an M2M connection and query your clients’ tax account, public debt and missing returns in one place. NAV’s pre-validation and responses come with clear explanations, so you see what to fix before you submit.

Upload a form as finished XML or fill it in on screen from NAV’s templates, and attach supporting files according to the form’s rules. You start the submission, then follow NAV’s confirmation and arrival number in the same place — for one company or many accounting-firm clients.

No XML, API or IT knowledge needed
Free consultation and trial

What SimplyX gives you for NAV M2M

SimplyX is a browser-based NAV M2M platform for companies and accounting firms: form filing, taxpayer queries and NAV feedback in one workspace. No XML, API or M2M expertise is needed — SimplyX handles the technical side of the NAV connection. You make the professional decisions and you submit the form from SimplyX.

Any form, with NAV pre-validation

Upload finished XML or fill in the form from NAV’s official templates. Run NAV’s pre-validation before you submit, so you fix errors while there is still time.

Finished XML upload or guided filling from NAV templates
NAV validation rules applied while you fill in the form
Attachments added according to the form’s rules

Client data in one step, for every company

No need to query tax accounts, public debt and missing returns client by client: one query covers every company you manage, and you see at once where action is needed.

Summary and itemised tax account
Public debt balance and missing returns
Insured-status data, exportable reports

Clear NAV responses, trackable status

See NAV’s errors and warnings with an explanation: what the message means, which field it affects and what to do. Follow the submission status and arrival number after filing, too.

NAV errors and warnings explained
Arrival number and processing status
Pre-validation and submission can be repeated

More for NAV M2M

Multiple companies and clients, with roles: Set per company who may query, who prepares and who submits a form.
Key handling as NAV requires: NAV M2M credentials are stored encrypted, users can enter and delete them themselves, and operations are logged for at least 90 days.
eVAT and NAV M2M in one place: VAT returns and other forms are prepared side by side, with the same companies and permissions.
Help with NAV M2M registration: We guide you step by step through user registration and activating the connection.
New NAV forms as NAV opens them: NAV is opening forms on its new document interface gradually; we track the templates alongside NAV’s announcements.
Trial in NAV’s test environment: Try a submission in NAV’s test environment before you go live.

How to start

Free consultation: We show you how your forms and client base would look in SimplyX.
Trial in the test environment: You submit one of your real forms to NAV’s test environment and walk through the process.
Live use: After NAV M2M registration and permission setup, you file forms in production.

What is NAV M2M?

M2M stands for machine-to-machine. According to NAV, NAV M2M enables electronic form submission through a general machine interface: a software developer’s client application communicates with NAV servers, and the end user uses that client application to submit electronic forms.

This does not mean that every human decision or approval disappears. Permissions, registration, professional data preparation, review and accountability remain on the customer’s side. The machine connection provides the infrastructure for technical data exchange and submission.

After ÁNYK is phased out, the practical question is often “what should we use instead?”. There is no single answer: depending on the tax type, the form and the process, ONYA, web eVAT, eVAT M2M or general NAV M2M may be the right route. For VAT returns, the main direction is the eVAT system: web interface or M2M.

Which digital channel fits which process?

The right route depends on the obligation, data volume, source systems, and required controls.

Channel	When can it fit?	Key consideration
ONYA	Supported forms and smaller workflows manageable in a browser	It is not a general M2M integration and is not the VAT-return channel.
NAV M2M	Recurring, higher-volume electronic form and document workflows	Requires a client application, registration, API key, and controlled permissions.
Web eVAT	Smaller VAT-return workflows that remain manageable in a browser	NAV data is supplemented and approved manually through the web interface.
eVAT M2M	VAT returns prepared from ERP, accounting, or an external filing platform	A separate VAT-specific data, validation, and approval process.

What does NAV M2M mean in practice?

NAV M2M is primarily a technical connection model. Business value appears when the client application, permissions and professional review work together.

Machine filing of forms

According to NAV, forms that could be filed in ÁNYK can be submitted over NAV M2M with attachments — including forms already disabled in ÁNYK.

Taxpayer data queries

With power of representation, you can query a client’s tax account, public debt, missing returns and insured-status data.

Client application and API key

The connection requires a client application built and registered by a software developer; the end user uses it with an API key after registration.

For VAT returns: eVAT M2M

For VAT, general M2M is not enough: eVAT M2M is a separate process with NAV data retrieval, VAT records, validation and draft-return approval.

What can NAV M2M do today?

NAV M2M is not one service but several machine interfaces that NAV is expanding step by step. According to NAV, these are available today:

Form filing: machine submission of forms that could be filed in ÁNYK, with attachments — including forms already disabled in ÁNYK.
Taxpayer data queries: live since 6 October 2025 — summary and itemised tax account, public debt balance, missing returns and insured-status data, with power of representation.
New document interface: live since 3 August 2026, starting with form NAV_F10; NAV is opening further forms gradually, and more than a dozen can already be tried in the test environment.
Organisational registration: since February 2025, organisations can register as well as individuals; the legal representative performs the registration.

How to choose a NAV M2M solution

NAV does not provide an installable M2M application: the connection requires a client application built and registered by a software developer, and NAV has published operating requirements for these. Questions worth asking:

Which forms does it support? Finished XML, guided filling or both — and does it follow NAV’s new templates?
Does it validate before submission? Does it run NAV pre-validation and show errors clearly?
How does it handle multiple clients? Can you see all clients in one place and control who may do what?
How does it store NAV credentials? NAV requires encrypted storage, keys the user can enter and delete, and a log of at least 90 days.
Can it query taxpayer data? Tax account, public debt, missing returns — one client at a time or many at once.
Does it handle eVAT too? If you also file VAT returns, one workspace is simpler.

NAV M2M wiki: client application requirements (Hungarian)

Which channel replaces ÁNYK for each process?

NAV’s announcement of 15 October 2026 proposes a gradual ÁNYK phase-out by return and form. The largest companies would move to mandatory eVAT during 2027; no exact start date has been specified, and 1 January 2027 is not fixed. For most VAT filers, including SMEs, the proposed start is 1 January 2028. Personal income tax and corporate income tax returns would remain fileable in ÁNYK during 2027. This is a proposal, not final legislation; the precise scope and dates require further official announcements.

ONYA and some NAV web interfaces are browser-based. The eVAT web interface can suit smaller, less complex VAT returns. eVAT M2M is the route for companies with higher document volumes or ERP/accounting-system data. NAV M2M is the channel for machine filing of other forms and for taxpayer queries.

NAV · 2026-10-15 · ÁNYK / eÁFA

Who should use NAV M2M?

NAV M2M is relevant mainly for those who work with business or filing software, have recurring tax obligations, and cannot scale manual, browser-based work.

Accountants and tax advisers handling many clients’ forms and tax accounts.
Larger companies with many documents and several systems.
Companies that want a traceable, auditable digital process after 2027 instead of manual workarounds.

Frequently asked questions

Is the mandatory eVAT start date fixed?

What does NAV M2M mean?

NAV M2M is a machine-to-machine connection: a general machine interface through which client applications connected to NAV servers can file forms and query taxpayer data.

Which forms can be filed over NAV M2M?

According to NAV, forms that could be filed in ÁNYK, with attachments — including forms already disabled in ÁNYK. On NAV’s new document interface forms arrive gradually: NAV_F10 has been live since 3 August 2026, and more than a dozen are available in the test environment.

Which NAV M2M solution is best?

The one that supports your forms, runs NAV pre-validation before submission and explains errors clearly, handles multiple clients, and stores credentials encrypted as NAV requires. If you also file VAT returns, choose one that handles eVAT too.

Does NAV provide its own M2M application?

No. According to NAV, it does not provide an installable M2M client application; the connection requires a client application built and registered by a software developer.

Can clients’ data be queried over NAV M2M?

Yes. Since 6 October 2025 the summary and itemised tax account, public debt balance, list of missing returns and insured-status data can be queried in production. The requester needs power of representation for the taxpayer.

Is NAV M2M the same as eVAT M2M?

No. General NAV M2M serves machine form filing and taxpayer queries, whereas eVAT M2M is the eVAT system’s separate machine channel for VAT returns.

Can a company register, or only an individual?

According to NAV, organisations can register since February 2025; the organisation’s legal representative performs the registration in the M2M registration application of the NAV Customer Portal.

What does an accounting firm gain with NAV M2M?

With many clients, forms and recurring tax tasks, a machine connection replaces repetitive browser-based work: form filing and client tax-account queries happen in one place, traceably.

Primary professional sources

Free tools and references

NAV M2M error codes — All 81 result and error codes generated from the NAV OpenAPI specs.
NAV M2M explained — Client programs, user registration, API key and document concepts.
ÁNYK route chooser — Three questions to identify the right filing channel.
eVAT M2M guide — The separate channel for the VAT return, with its own interface.