Tools for entrepreneurs
Data box for the self-employed in 2026
The data box (datová schránka) is the only genuinely mandatory “tool” of every self-employed person (OSVČ) — the state set it up for you automatically and free of charge by law, without you having to apply for it. Once it is made accessible, you file your overviews and your tax return through it electronically. We will show you how to activate it and what you are required to handle through it from 2026.
What a data box is and why you have one as a self-employed person
The data box is a repository for electronic communication with public authorities and the state. A message sent through the data box has the same legal validity as a registered letter — except you handle it from your computer or phone, anytime and free of charge.
Since 1 January 2023, the state has been setting up data boxes automatically and free of charge for all self-employed natural persons (trade-licence holders and other OSVČ) under the amendment to Act No. 300/2008 Coll., on electronic acts and authorised conversion of documents. So you do not apply for anything — the box was created for you automatically after your entry in the Trade Register, and your access credentials were sent to you by post. (source: czechpoint.gov.cz; verified 2026)
Suspending (interrupting) your trade has no effect on the existence or accessibility of the data box — you have the box even during the pause and you must keep checking it. (source: VZP ČR; verified 2026)
How to activate and set up the data box (step by step)
- Find the access credentials from the Ministry of the Interior After the box was set up, they were sent to you by post for personal delivery. They contain a username and a one-time password for the first login.
- Log in at mojedatovaschranka.cz The first login activates the box (makes it accessible). You can also log in via Citizen Identity (Identita občana) — using bank identity, the eObčanka electronic ID card, or the eGovernment mobile key.
- Count on automatic activation within 15 days Even if you do not log in yourself, the box becomes accessible automatically once 15 days have elapsed from the date the access credentials were delivered. From that point, official deliveries made by authorities to the box have legally binding effect.
- Set up e-mail and SMS notifications In the box settings, enable notifications of newly delivered messages to your e-mail address (free) or by SMS (charged). Without notifications you can easily miss an official notice and the deemed-delivery rule will apply.
- Add access for your accountant or tax adviser You can grant authorisation to another person (e.g. an accountant) to read messages and file on your behalf. You set this up in the Settings → Users section.
- Check the box regularly Open the box at least once a week. A message is deemed delivered no later than on the 10th day after delivery, even if you do not open it (the deemed-delivery rule).
Caution: from 2026 you must file through the data box electronically
If your data box is accessible, you file exclusively electronically. From 1 January 2026, the obligation to file electronically now also extends to the overview for the health insurance company (previously it could be filed on paper too) — in addition to the already applicable obligation for the overview for the ČSSZ (Czech Social Security Administration; e-Submission in XML format, box ID 5ffu6xk) and for the tax return. For filing in the incorrect (paper) form where the law requires electronic filing, a fine of up to 50,000 Kč may be imposed (Tax Code, Act No. 280/2009 Coll.). And do not forget about deemed delivery: an official message is deemed delivered no later than on the 10th day after it is deposited in the box (§ 17(4) of Act No. 300/2008 Coll.), even if you do not read it — so check the box regularly. (sources: cssz.gov.cz, VZP ČR, ČPZP; verified 2026)
Deadlines for the 2025 overviews filed through the data box in 2026
| Method of filing the tax return | Overview for the ČSSZ (OSSZ) | Overview for the health insurance company |
|---|---|---|
| On paper (those without a data box) | by 4 May 2026 | by 4 May 2026 |
| Electronically through the data box | by 1 June 2026 | by 4 June 2026 |
| Prepared by a tax adviser | by 3 August 2026 | by 3 August 2026 |
The overview must be filed no later than 1 month after the deadline for the tax return. Anyone with an accessible data box is required to file both the overviews and the return electronically. Any shortfall of insurance contributions is payable within 8 days from the day the overview was (or should have been) filed. Source: ČSSZ (cssz.gov.cz), VZP ČR; verified 2026.
Everything you can handle through the data box
Income and expenses overviews
The annual income and expenses overview for the ČSSZ (e-Submission XML, ID 5ffu6xk) and for the health insurance company — from 2026 both must be filed electronically.
Tax return
If your data box is accessible, you must file the income tax return with the tax office electronically; otherwise you risk a fine.
Communication with authorities
The trade licensing office (živnostenský úřad), the tax office, ČSSZ, and the health insurance company deliver decisions and notices directly to your box.
Notifications and registrations
You can send changes to your details, notification of the commencement or suspension of activity, and other filings without visiting an office, free of charge.
Frequently asked questions about the OSVČ data box
Must a self-employed person have a data box?
How do I activate the data box?
What is deemed delivery and why should you watch out for it?
What do I handle through the data box as a self-employed person?
Do I face a fine if I file on paper instead of through the data box?
How much does maintaining a data box cost?
File your overviews and return without mistakes
Your data box is active — now put it to use. Go through the guide on OSVČ overviews and the tax return so that you meet all the deadlines and avoid fines.