NAV M2M and the gradual ÁNYK transition: an accounting guide
NAV M2M preparation for accounting firms: channels, permissions and client plans. NAV’s 15 October proposal calls for a gradual ÁNYK transition.
What exactly is being discontinued, and what isn't?
On 15 October 2026, NAV proposed a gradual ÁNYK phase-out by return and form. The largest companies would move to mandatory eVAT during 2027, but no exact start date has been announced: 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 through ÁNYK during 2027. This is a NAV proposal, not final legislation; the detailed scope and exact dates require further official announcements. Accounting firms should select a channel for each obligation and prepare a client-by-client implementation plan.
According to NAV, more than 30 million forms are submitted to ÁNYK annually. This traffic will migrate to two channels: ONYA (manual, browser-based completion, for lower volumes), and the NAV M2M general machine interface (automated, software-initiated submission, primarily for accountants, tax advisors, finance and accounting professionals, and larger taxpayers).
Anyone currently using ÁNYK in practice faces two decisions: which channel they will work on, and with what software. The question is professional in nature, not merely technical.
What does M2M mean in accounting practice?
M2M (machine-to-machine) simply means that a registered software communicates directly with NAV's system. From an accountant's perspective, this has three important implications.
First: there is no separate "M2M login." After a single registration, the software manages — based on existing power of attorney authorizations — on whose behalf it can perform data communication.
Second: batch submission of returns is a native part of the process. What worked as batch submission in ÁNYK is even more automatable in M2M — scheduled, combined with approval logic, initiated from business management software.
Third: submission and status tracking are guaranteed. The receipt and error notification arrive in the storage space and, in properly designed software, can be linked back to the original return.
It is important to clarify a misconception: NAV does not provide a "downloadable M2M client." M2M is intentionally a developer tool; software companies build products on top of it that they make available to end users (accountants, accounting firms, businesses).
Where does M2M stand now? (And what does this mean in practice?)
The system has been live since early October 2024. According to data NAV presented at the National Tax Consultation in autumn 2025, about 50 registered client programs and 700 registered taxpayers were using it at that time — still far from ÁNYK's annual volume of more than 30 million forms, but the direction is clear.
Two important milestones occurred recently: in February 2025, legislative amendments made it possible for organizations — not just natural persons — to complete end-user registration; and on October 6, 2025, the data query service launched in the live environment.
As an initial query package, the following can be queried: tax account data, employment notifications, list of missing returns, and public debts transferred for enforcement. Based on market feedback, the query channel is stable and provides daily operational value to those who integrate it into their workflows.
What's coming in 2026? NAV's roadmap
Based on milestones published on the NAV GitHub wiki, 2026 will be the year of the new Document API. This does not replace the existing API but goes live alongside it, built on more transparent, modern document formats instead of the old ÁNYK structure.
| Proposed timetable | Action / status |
|---|---|
| 15 October 2026 | NAV proposes a phased approach instead of a universal cut-off; not final legislation. |
| During 2027 — exact date unspecified | eVAT transition for the largest companies; 1 January 2027 is not fixed. |
| 1 January 2028 — proposal | Proposed eVAT start for most VAT filers, including SMEs. |
| Other returns and forms | Gradual phase-out; PIT and corporate income tax would remain fileable in ÁNYK during 2027. |
According to NAV, these are planned dates and may change — but the direction is stable.
The new API brings two significant professional innovations. One is that NAV will publish return-completion rules — instead of the previous PDF completion guides — in a format that accounting software can directly read and automatically apply; a rule change therefore no longer needs to be manually tracked with every software update. The other innovation is a real-time validation service, with which the software can query NAV before submission to check whether a given return is in order. Both serve the same goal: errors should appear on the accountant's own screen, not after NAV-side processing in an already-submitted return.
Four decisions before the end of 2026 — what does an accounting firm need to handle now?
The transition is not an IT project, but four interconnected professional decisions.
1. Representation and registration structure
Questions to clarify: who registers within the accounting firm on the ÜPO (Client Portal)? How does M2M registration connect to existing standing authorizations? Who manages the API keys?
These are not hypothetical questions. Responsibility for M2M operations lies with the registrant: the person themselves for an individual registration, or the legal representative for an organisational registration — so in an accounting firm, it is not only the software that needs to be set up, but the chain of responsibility must also be defined.
2. Software selection (or coordination with your vendor)
The practical question is simple: does the payroll software, accounting software, or tax software currently in use already support M2M, and if so, at what pace will it also support the new Document API? If the current vendor does not yet support it, what is the development timeline? If it does, what features are supported (submission only, or also data querying)?
These are questions that need to be asked in the first half of 2026, so there is time to test by year-end and switch if necessary.
3. Client communication
Explain which channel the firm will use for each client’s obligations, what preparation is needed and when a change is expected. NAV’s 15 October proposal does not establish a universal final start date for every client.
In most cases, the answer is: the accounting firm handles it, but it is worth informing clients.
4. Internal processes and risk management
An accounting firm is by nature a risk concentration point. If something goes wrong, it causes problems for many clients' returns simultaneously. NAV M2M requirements (encryption, logging, audit trail) are not optional considerations — the chosen software must mandatorily fulfill these.
NAV's client program requirements — including secure storage of identification keys, auditability of user operations, and deletion of keys upon termination of access — are obligations that apply to the software.
Typical mistakes that can be avoided now
Procrastinating until the second half of 2026 — it is worth consulting with experts and beginning preparation now.
Confusing NAV M2M with eÁFA M2M — these are two separate channels with separate rule systems.
The misconception of building your own client program — most accounting firms should not develop their own client.
Mixing test and live environments — the test API key is not valid in the live environment.
Skipping data querying — which can already save daily minutes in practice today.
What should you concretely do now?
The remaining time is short from a professional standpoint. A reasonable schedule includes the following steps:
Before summer 2026: clarify representation and registration structure, complete M2M registration, hold first consultation with software vendor.
Summer–autumn 2026: finalize software selection, testing, integrate available M2M features into daily work (the new Document API has been live since August 3, 2026).
Autumn–winter 2026: finalize internal processes, client communication, submit the last ÁNYK returns, run parallel operations.
Transition by obligation: follow the final NAV timetable and available channels for each form; the eVAT proposal does not set a phase-out date for all NAV M2M forms.
NAV M2M is itself a well-documented, live technology. The question is not whether the transition is possible — it is, and an ever-growing share of the market is already using it, but many changes will still appear in the near future, so it is worth starting preparation and familiarization with the system now.
Frequently asked questions
How long can ÁNYK still be used?
On 15 October 2026, NAV proposed a gradual ÁNYK phase-out by return and form. The largest companies would move to mandatory eVAT during 2027, but no exact start date has been announced: 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 through ÁNYK during 2027. This is a NAV proposal, not final legislation; the detailed scope and exact dates require further official announcements.
Is the use of NAV M2M mandatory?
No, it is an alternative channel. NAV recommends M2M primarily for accountants, tax advisors, and larger taxpayers who submit many returns or want software integration. Those who handle returns manually in small volumes can continue using ONYA for supported forms.
What is the difference between NAV M2M and eÁFA M2M?
These are two separate channels. The general NAV M2M is built for a wide range of documents (typically replacing ÁNYK forms), while eÁFA M2M is a separately designed system specifically for VAT return submission, with its own XSD and business process. The two do not replace each other, but coexist in parallel.
Is separate registration required for each client business?
No. An accounting firm needs only a single M2M registration; NAV manages — based on existing power of attorney authorizations — on whose behalf the software can act. This is one of the greatest practical advantages over browser-based ÜPO solutions.
Can a company or accounting firm register for M2M, or only a natural person?
Both, since February 1, 2025. With the introduction of M2M 2.0, organizational registration is also possible, so accounting firms, accounting organizations, and any business entity can register as a user in their own name.
Do we need to develop our own software for M2M?
The vast majority of accounting firms do not. NAV intentionally designed M2M so that software companies build products on top of it; the relevant question for a practice is whether the business management or return software currently in use already supports M2M. Developing your own client program is only justified for special internal integration needs.
What can be queried via M2M?
Available in the live environment from October 6, 2025: tax account data (aggregate and itemized), employment-related notifications, list of missing returns, and public debts transferred for enforcement. NAV has indicated that the package will expand.
When must we transition, and how should we prepare?
On 15 October 2026, NAV proposed a gradual ÁNYK phase-out by return and form. The largest companies would move to mandatory eVAT during 2027, but no exact start date has been announced: 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 through ÁNYK during 2027. This is a NAV proposal, not final legislation; the detailed scope and exact dates require further official announcements. Plan preparation for each obligation and client: data assessment, channel selection, permissions, testing and professional approval. Keep internal project dates separate from filing due dates and the transition proposal, which is not final.
How much does the M2M transition cost?
The cost typically arises in the licensing of the chosen software and any internal process development.
Where can official NAV resources be found?
NAV publicly publishes the complete technical documentation, milestones, FAQ, and schema descriptors for M2M at github.com/nav-gov-hu/M2M. The wiki, SwaggerHub API descriptor, and the developer Discussions forum are also available there.
Sources
NAV: less administration, fewer errors – moving to data-based platforms (5 December 2025, Hungarian)
Government Decree 322/2024 (XI. 6.), Section 152(13) (Hungarian)
NAV eVAT GitHub: correcting returns filed via ÁNYK (NAV answer, Hungarian)
NAV: M2M interface opened to organisations (10 February 2025, Hungarian)
NAV M2M wiki: questions and answers (Hungarian)
NAV: ÁNYK phase-out presentation, National Tax Consultation 2025 (PDF, Hungarian)