The effects of automatic data boxes from January 2023

As of 1 January 2023, Act No. 457/2022 Coll. (hereinafter referred to as the “Act”) amending Act No. 300/2008 Coll., on Electronic Acts and Authorised Document Conversion, as later amended, and other related laws, extends the circle of persons to whom data boxes are established automatically by law. Compared to the original legislative plan, data boxes (namely data boxes of the type “data box of a natural person”) are not legally established by law for the persons not performing business activity. Nevertheless, such persons may have a data box of a natural person established based on the request.

The area of data boxes falls under the competence of the Ministry of the Interior and detailed information on data boxes is published in electronic form on the website for data boxes ( and on the website of the Ministry of the Interior at The main goal of this massive expansion of data boxes is primarily to increase efficiency and speed up communication between state institutions and the public.

Who is supposed to have a data box automatically established by law

Effective from 1.1.2023, a data box is to be “automatically” established by law:

  • for any legal entity registered in the register of entities – thus not only legal entities established by law, legal entities registered in the Commercial Register and organisational units of foreign legal entities registered in the Commercial Register, as was the case in 2022, but also legal entities that are not established for the purpose of doing business, such as foundations, associations or partnership of apartment owners;
  • for natural persons doing business entered in the legally specified records or registers - until now the data boxes of these persons (typically self-employed persons) have only been established on the basis of their request, but now the data box of a “natural person doing business” is established by the Ministry of the Interior “automatically”.

Data boxes for natural persons without businesses will be established solely upon their request, as has been the case so far.

Effects of the established data box

Once a person has access to a data box established by law, he/she will be obliged to submit forms (e.g., tax returns, registration applications, etc.) to the tax authorities exclusively electronically in the format and structure prescribed by the tax administrator. He/she does not, however, necessarily need to use the data box to do so, he/she can also submit it via the tax administration portal.

From the perspective of the creation of the obligation to file a tax return electronically in connection with the existence of a data box, the decisive moment is no longer the establishment of the data box by law according to the valid legislation, but only when it is made accessible. This will be done when one of the persons defined by the Act first logs in (the access data is sent by the Ministry of the Interior immediately after the establishment of the data box), but no later than the 15th day after the date of the delivery of the access data to these persons.

The existence of an obligation to file a return exclusively electronically is assessed at the moment when the tax return is filed in relation to a particular individual. If the entrepreneur already has an active data box at the time of filing the return in 2023, the submission must only be made electronically, but if the data box is not yet active, he/she can file the return in paper form.

The access to the data box also has a significant impact on the form of communication with the tax offices (and their territorial branches) and on the delivery of documents on the part of the bodies of the Financial Administration of the Czech Republic.  Data box owners will have documents related to their business activities delivered exclusively to their data boxes, other non-business-related documents will be delivered by post even after the establishment and the access of the data box by the natural person.

How long are the messages in the data box available?

Messages in the data box are available for 90 days, after which they are automatically deleted and the user can no longer get at messages older than 90 days directly through the data box. However, he/she has the possibility to use the additional paid Data Safe service, or to download the data message to a computer (or to a mobile phone, or to any data carrier), or to archive the data message on the Citizen Portal (free capacity up to 500 MB). Communication via data boxes with public authorities is free of charge, but there is a charge for commercial messages addressed to, for example, banks, insurance companies, energy suppliers, etc.

Fiction of delivery on weekends and holidays

The law contains an adjustment to the fiction of delivery of a data message, according to which the document (data message) sent by a public authority is considered to have been delivered upon the expiration of 10 days from the delivery of the document to the recipient's data box. The Supreme Administrative Court has recently addressed the question of the moment of delivery in cases where the fiction of the moment of delivery of a data message falls on a Saturday, Sunday or public holiday. It follows from the Supreme Administrative Court's conclusion that, as of 1 January 2023, a new rule is introduced that determines that on Saturday, Sunday and public holidays, data messages that the user has not yet opened will not be automatically delivered and the last day of the period of the fiction of delivery will be the closest following working day.

If you have any question related to data boxes, please do not hesitate to contact our specialists.


Gabriela Ivanco, Tax Manager 
Anna Klímová, Editor, Mazars Tax View