Datová schránka — national legal inbox

Datová schránka (DSZ) is the Czech electronic legal inbox, created by Act No. 300/2008 Coll. and activated on 1 July 2009. It carries probative value equivalent to registered mail with acknowledgement of receipt. Originally mandatory for every administration and legal entity, it became universally mandatory for every OSVČ entrepreneur on 1 January 2023 — one of Europe's first qualified registered delivery systems to reach 100% of a country's entrepreneurs.

History — 2008 act, 2009 activation, 2023 OSVČ extension

DSZ emerged from the same act as ePodatelna: Act No. 300/2008 Coll. The Ministry of Interior (MV ČR) set the principle of a single enforceable legal electronic gateway, operated by Česká pošta with a state guarantee. On 1 July 2009, every administration and every legal entity registered in the Obchodní rejstřík had its DSZ activated automatically.

The January 2023 extension (Act No. 261/2021 Coll., adopted in 2021 but entered force 14 months later) marked a paradigm shift: every self-employed individual (OSVČ) must now have an active DSZ, whether they use it or not. This covers ~1.2 million Czech self-employed.

2008       | Adoption of Act No. 300/2008 Coll. on electronic acts —
           | joint creation of ePodatelna + Datová schránka (DSZ).
           |
2009       | 1 July: mandatory Datové schránky activated for every
           | public administration + legal entities registered in
           | the Obchodní rejstřík.
           |
2009-2010  | Mass activation: 800,000 inboxes opened in 6 months.
           | Court notifications from Justice.cz transit through DSZ.
           |
2014       | Technical overhaul — strict HTTPS, NIA identity (Národní
           | bod pro identifikaci a autentizaci) integration.
           |
2018       | eIDAS Regulation 910/2014 transposed. DSZ identified as a
           | qualified electronic registered delivery service
           | (Article 44 eIDAS) — EU recognition.
           |
2020       | Czech POINT enables authorised paper → DSZ document
           | conversion with legal value (autorizovaná konverze).
           |
2022       | Act No. 261/2021 Coll. — mandatory DSZ extension to OSVČ
           | (osoba samostatně výdělečně činná, registered self-employed
           | individuals).
           |
2023       | 1 January: entry into force — every self-employed
           | individual must have an active DSZ. ~700,000 new inboxes
           | opened.
           |
2024-2026  | ~3.3M active inboxes (administrations, companies, OSVČ,
           | volunteer individuals). ~140M messages / year exchanged.

Governance — MV ČR + Česká pošta

Two actors co-manage DSZ:

• MV ČR (Ministry of Interior) — legal sponsor, publishes implementation decrees, supervises the operator.
• Česká pošta s.p. (Czech Post, public establishment) — exclusive technical operator since 2009. Guarantees availability, 10-year archiving, qualified timestamping.
• NÚKIB — cyber requirements (TLS 1.3, encrypted archiving). For qualified electronic registered delivery services under eIDAS Article 44, audits are conducted jointly by ministry and NÚKIB.
• ÚOOÚ — Office for Personal Data Protection, oversees data processing in DSZ (especially for individuals).

Schema — 7-char DSZ ID + ZFO

# Datová schránka — sample ID and structure

ID format    : 7 alphanumeric characters
  Real examples:
  - 48ia97h  → Magistrát hl. m. Prahy (Prague city hall)
  - 8gxaaur  → Ministry of Finance CZ
  - bhgaip4  → GFŘ (General Financial Directorate)
  - sapaiyv  → Justice.cz (registry)

Portal URL   : mojedatovaschranka.cz
API          : ISDS Web Service (Informační systém datových schránek)
               https://www.mojedatovaschranka.cz/ISDS/

Inbox types:
  - OVM   : Orgán veřejné moci (administration)
  - PO    : Právnická osoba (legal entity)
  - PFO   : Podnikající fyzická osoba (OSVČ — mandatory since 2023)
  - FO    : Fyzická osoba (individual — voluntary)

Message format: ZFO (Zaručený formát obsahu)
                or PDF/A, ISDOC, XML, ODT, DOCX attachments

Probative value: equivalent to registered mail with receipt
  → 10 days after deposit = irrebuttable presumption of receipt
  → procedural deadlines run by operation of law

Cost          : FREE for life for normal legal use
                (Česká pošta charges "postovni datova zprava" messages
                for private peer-to-peer individual communication).

The DSZ ID is unique, attributed by MV ČR at activation. It is not derived from IČO or name — it is a technically opaque 7-character alphanumeric identifier. The ISDS API (Informační systém datových schránek) exposes deposit, read, acknowledgement, and public directory search services.

Datová schránka vs ePodatelna vs eIDAS

Adoption — ~3M active inboxes

• ~14,000 OVM inboxes (administrations) — ministries, regions, municipalities, courts, independent agencies.
• ~750,000 PO inboxes (legal entities) — s.r.o., a.s., k.s., v.o.s., družstva registered in the Obchodní rejstřík.
• ~1.2M PFO inboxes (self-employed OSVČ individuals) — mandatory since 1 January 2023.
• ~1.3M FO inboxes (volunteer individuals) — free activation via NIA, steady growth since 2018.
• ~140M messages / year (2024 volume published by Česká pošta) — administrations to companies, tax notifications, civil litigation, contracts.

Common pitfalls

• Not checking your DSZ. The 10-day counter runs automatically. An OSVČ who never opens their inbox may receive a GFŘ tax notification and be deemed to have read it, triggering a short payment deadline.
• Confusing DSZ and ePodatelna. DSZ = legal, ePodatelna = general correspondence. Sending a supplier invoice to an administration's DSZ is not guaranteed to be processed like a standard invoice.
• Fake address notification. The 7-char DSZ identifier is opaque. Any marketing communication claiming "your DSZ has been suspended, click here" is necessarily phishing — MV ČR and Česká pošta never solicit via DSZ for renewals.
• Wrong ZFO format. The ZFO format is Czech-specific, derived from Form Filler Software 602 (historically tied to the Software602 vendor). Foreign ERPs need a ZFO connector or must route via PDF/A.
• Delegation to an accountant. An OSVČ can delegate DSZ access to its accountant via NIA + ISDS proxy. But legal responsibility stays with the holder — the accountant is not a legal representative.

Cross-links

• Czech Republic hub — full overview
• ePodatelna — B2G inbox
• IČO + DIČ — Czech identifiers
• ISDOC — national XML standard
• ViDA — Czech roadmap
• PEPPOL — European standard
• mojedatovaschranka.cz — DSZ portal
• Act No. 300/2008 Coll.
• Česká pošta — DSZ operator