The Hungarian Tax Authority (HTA) will tighten the validation rules applied in the Online Invoice system starting from 15 September 2025, in order to further improve the quality of invoice data reporting and to achieve greater consistency in data submissions. 

The most significant change is that 15 validation rules, which previously appeared only as warnings (so-called WARN messages) in the system, will be treated as errors (ERROR) as of 15 September 2025. From a practical point of view, this means that if such an error occurs during invoice data reporting, the tax authority’s system will reject the data – in other words, the invoice will technically be treated as if it had never been submitted. HTA decision was justified by the fact that, based on past experience, businesses often ignored warning messages and did not correct errors in their invoicing or reporting processes, resulting in widespread data quality issues. 

As a result, the RTIR system will operate as follows:

• Three new WARN (warning) messages will be introduced to support more accurate detection and error prevention.
• Three currently active WARN messages will become inactive, meaning they will no longer be issued.
• One message previously classified as INFO will be reclassified as WARN, indicating that the case requires increased attention.
• 15 messages will be classified as ERROR, which means these issues will result in the rejection of the submitted data provision.

The exact codes and descriptions of the changes are available at the following link:
https://github.com/nav-gov-hu/Online-Invoice/discussions/1144

The new rules will come into effect on 15 September 2025, providing more time for businesses and developers to prepare. Before implementation, between 1 and 15 September, the changes can be tested in the HTA Online Invoice system’s TEST environment, which allows for the practical verification of developments and modifications. It is advisable to begin reviewing systems now and, if necessary, carry out the appropriate technical developments to ensure smooth and compliant data reporting from mid-September onward.