A tax return goes through a datová schránka (data box) as an XML attachment addressed to the competent tax office. Check the XML in the MOJE daně portal before you send it, and save the delivery receipt afterwards. For the 2025 personal income tax return the electronic deadline ran to 4 May 2026; anyone who filed electronically by 1 April stayed within the basic April deadline, including the date the tax fell due.
What a data box is and why you have one
A datová schránka is an electronic mailbox set up by the state for communication between individuals, companies and public authorities. A message sent from it carries the same legal weight as a registered letter with proof of delivery.
For an OSVČ (osoba samostatně výdělečně činná — a self-employed person) a data box is created automatically by law, since 1 January 2023 under the amendment to Act No. 300/2008 Coll. You do not apply for it — the state set it up on the basis of your živnost (trade licence). The access credentials were posted to the address in the trade register.
Key characteristics
- Legally binding — a message counts as delivered the moment you log in, or automatically on the tenth day after it arrives (the delivery fiction).
- Free of charge — sending messages to public authorities costs nothing.
- Short retention — messages stay in the system for 90 days and are then deleted. For longer storage you have to download them or pay for the Datový trezor (data vault) service.
- You have to check it — because a message is delivered whether or not you log in, the box needs checking regularly. Otherwise deadlines for appeals, statements or payments can pass without you noticing.
How to log in
There are several ways in; pick whichever suits you.
1. The web portal
Go to mojedatovaschranka.cz. You can sign in with:
- A username and password — sent to you in an envelope from Czech POINT or by post. You are asked to change the password on first login, and it expires every 90 days.
- NIA (the national identification and authentication point) at identity.tescosw.cz. You can use BankID (your bank's identity service), the eObčanka electronic ID card or MojeID.
2. The mobile app
The Datovka app is available for Android and iOS. After the first login (username and password, or NIA) you can switch to a fingerprint or a PIN.
3. The desktop app
For heavier users there is the desktop Datovka (open source), which manages several data boxes at once and downloads messages automatically.
Three ways to file electronically
There are three main routes. All of them assume you have the return ready in electronic form — an XML file.
Route 1: sending it straight from the data box
The most direct option if the XML is ready:
- Prepare the XML file — the tax return in XML format. You can generate it in accounting software or in an application built for the purpose.
- Log in to the data box at mojedatovaschranka.cz.
- Create a new message — "Napsat zprávu".
- Enter the recipient — the addressee is the tax office for your area. The data box ID of each office is published on the Financial Administration website (the Prague tax office, for instance, has several territorial branches, each with its own ID).
- Fill in the subject — for example "Přiznání k dani z příjmů fyzických osob za rok 2025" (personal income tax return for 2025).
- Leave "K rukám" and "Číslo jednací" empty unless you are answering a specific notice.
- Attach the XML file.
- Send it and save the delivery receipt.
Worth doing: name the type of filing and the tax period in the subject line. The office processes the message automatically, but a clear description makes it easier to identify.
Route 2: the MOJE daně portal
The MOJE daně portal (adisspr.mfcr.cz) is the Financial Administration's current interface, which replaced the older EPO front end. The steps:
- Log in through NIA — the same identity you use for the data box (BankID, eObčanka, MojeID).
- Choose the type of filing — for example the personal income tax return.
- Fill the form in online or upload an XML file.
- Check it and send it — the portal runs a basic validation and flags errors.
- Confirmation — you get a receipt in the portal as soon as it is submitted.
The advantage of MOJE daně is that you can complete the form in the browser without an XML file at all. The system walks you through the lines and keeps the running totals. For a first return it is the most comfortable route.
Route 3: the EPO forms
EPO (Elektronická podání pro Finanční správu — electronic filings for the Financial Administration) is the older interface, still reachable through the same portal at adisspr.mfcr.cz. The procedure resembles MOJE daně:
- Choose the type of filing.
- Upload the XML file or complete the interactive form.
- Sign the filing — through the data box, with an electronic signature, or send it unsigned and confirm it another way within 5 days (a signed paper confirmation, or a visit in person).
The extra month for filing electronically
The four-month deadline applies when the electronic return is not filed within the basic three-month one. It is not an automatic postponement for everyone who sends the form electronically:
- Paper filing: by 1 April (for 2025 that was 1 April 2026).
- Electronic filing: by 1 May (for 2025 it was 4 May 2026 — 1 May is a public holiday, so the deadline moved to the next working day).
If you filed electronically by 1 April 2026, the basic deadline applied and the tax was due on 1 April. For electronic filings made after 1 April, the extended deadline ran to 4 May 2026, and the tax fell due on that same day. The dates are confirmed by the Financial Administration.
Note: the obligation to file electronically covers every filing that has a prescribed XML format. That includes the personal income tax return (DPFO), the VAT return (DPHDP3), the control statement (DPHKH1) and other forms.
What you can file this way
Through a data box or the MOJE daně portal you can submit practically the whole tax agenda:
- Personal income tax return (DPFO / DPFDP7)
- VAT return (DPHDP3) — monthly or quarterly, mandatory for VAT payers
- VAT control statement (DPHKH1) — mandatory for VAT payers
- EC sales list — for trade within the EU
- The přehled (income and expense statement) for ČSSZ
- The přehled for your health insurance company
- Notice of starting, suspending or ending your activity
Common problems
Forgotten password
The data box password can be reset at any Czech POINT counter (a post office or a municipal office). If you log in through NIA or BankID, you do not need the box's own password at all.
You do not know the tax office's data box ID
The list of every tax office data box is published on the Financial Administration website. You can also search for a specific office by name directly in the data box system.
The XML file is rejected
If MOJE daně or EPO rejects your XML, the usual cause is the wrong file structure or an out-of-date form version. Make sure you are using the current XML schema for the year in question.
The delivery fiction
If you never log in, a message from an authority is treated as delivered on the tenth day after it arrived. That can matter a great deal — the deadline to appeal against a tax office decision can run out. So check the data box at least once a week, and ideally set up e-mail or SMS alerts for new messages.
Setting up notifications
- Sign in at mojedatovaschranka.cz.
- Go to Settings.
- Under "Upozornění" (alerts), enter an e-mail address or a phone number.
- Choose what you want to be told about (a new message, a delivery receipt and so on).
The whole thing, step by step
- Get the supporting records together — the book of income and expenses, proof of income, confirmation of the insurance advances you paid, and documents for any tax reliefs.
- Produce the XML file of the return — in accounting software or directly in MOJE daně.
- Log in to MOJE daně or to your data box.
- Upload the XML or complete the form online.
- Check the figures — the portal validates the filing; read what it reports.
- Send it and save the receipt.
- File the přehled statements with ČSSZ and your health insurance company (within one month of the deadline for the income tax return).
Where to get a valid XML file
If you would rather not fill the forms in by hand in MOJE daně, you need an XML file produced by software that follows the Financial Administration's current schemas. Taxorio generates valid XML for the VAT return (DPHDP3), the control statement (DPHKH1) and the personal income tax return (DPFDP7). XML export is part of the PRO plan. You download the file and upload it to the data box or to MOJE daně — nothing to retype, and no transcription errors.
Keeping your income and expense records in Taxorio through the year also means the figures are ready when the deadline comes: check them, generate the XML and send it, instead of hunting for documents at the end of March.
Taxorio scope: Taxorio provides invoicing and income/expense records for Czech sole traders. It is not full accounting or personalised tax advice. For an unsupported or unusual case, verify the treatment with a Czech accountant or tax adviser before filing.