Hungary: Upcoming Changes to Real-Time Reporting Validations in 2025

The Hungarian Tax Authority (NAV) has announced important changes to the Online Számla (Online Invoice, i.e., real-time reporting) system validations. After a two-month public consultation period, several industry feedback points have been taken into account, leading to adjustments in the validation concept. These refinements aim to improve data accuracy and quality, which benefits both NAV and taxpayers using its services.

The new validation rules will apply from 15 September 2025, with testing available from 1 September 2025.

Key Changes in Validation Rules

• Three new WARN messages will be introduced.
• Three existing WARN messages will become inactive.
• One INFO message will be reclassified as WARN.
• 15 WARN messages (instead of the originally planned 21) will now function as ERROR.

What this means in practice

• ERROR messages block data submission. If a technical or content error is flagged as ERROR, the invoice data will not be accepted.
• WARN messages do not block submission, but they still signal business-level issues. An invoice flagged with a WARN may contain inaccurate or incomplete data, so it should be reviewed and often corrected.

Summary of Planned Validation Changes

The tightening of validations is designed to improve data quality, as experience has shown that many taxpayers do not pay enough attention to warning messages. While warnings have highlighted anomalies in data provision or invoicing processes, ignoring them has led to incomplete or incorrect data, which can cause significant problems both in the Online Invoice system and in downstream processes such as the operation of the eVAT system and the digitalization of client accounting.

From September 2025: Warnings Become Errors

Starting 1 September 2025 in the test system and 15 September 2025 in the live system, 15 existing warnings will be reclassified as errors. Once this change takes effect, submissions with these issues will be blocked until corrected.

Common examples include:

• Incorrect dates – such as when the closing date of a performance period is earlier than the opening date (ID 330).
• Exchange rate errors – for example, extreme values or mismatches with the HUF currency (ID 1310).
• Missing data – such as when a collective invoice line does not include a completion date (ID 620).
• Wrong VAT designations – affecting several scenarios (IDs 581–584, 591, 593, 596, 701).
• Invoice modification issues – such as duplicate or unrealistic modification numbers (IDs 560, 1150).

If your invoicing program has triggered these warnings in the past, it will now receive errors for the same issues, making timely corrections essential.

Changes to Other Validations

• INFO message tightened: Validation 11400 (unintended modification delivery date) will now run as a warning, alerting users to date inconsistencies without blocking submission.
• Three warnings deactivated: IDs 690, 700, and 1301 will no longer run, as they are no longer relevant under the new rules.

New Warnings to Improve Data Consistency

NAV will also introduce three new warning validations:

• ID 435 – flags when a VAT rate appears in the invoice summary without a corresponding line item.
• ID 734 – highlights mismatches between VAT line totals and summary data.
• ID 1311 – detects incorrect VAT status data, for example when a domestic VAT taxpayer is reported as “OTHER.”
• These new warnings will not block submissions, but they aim to ensure more accurate and consistent reporting across invoices.

NAV has stressed that the goal is not to increase the volume of errors, but to encourage higher quality and consistency of data provision. The validations will continue to be monitored, and further changes will be based on observed improvements in data quality.

Why These Changes on Real-Time Reporting Matter?

Accurate and complete invoice data is essential not only for NAV but also for companies that rely on machine-to-machine connections or web-based query services in both the Online Számla system and the growing eÁFA platform. Correct invoice data ensures that reporting obligations are fulfilled smoothly and that businesses avoid downstream compliance risks.

Companies should already start coordinating with their IT and tax compliance teams to ensure readiness:

• Review NAV’s feedback messages regularly to identify recurring issues.
• Work closely with developers to ensure invoicing software adapts to the new requirements in time.
• Test systems from 1 September 2025 to detect and resolve potential issues before the live launch on 15 September 2025

The detailed list of validation changes is available on NAV’s GitHub discussion page. Also, find the official NAV’s announcement about the entering into force of stricter validations.

How Marosa Can Help

At Marosa, we understand that regulatory changes such as the tightening of Online Invoice system validations can create significant challenges for businesses operating in Hungary. Our team of VAT compliance specialists supports multinational companies in adapting to these new requirements smoothly and efficiently. By partnering with Marosa, your company can focus on business while we take care of the technical and compliance complexities of Hungarian VAT reporting.