Skip to content
Guide API Spec
Section navigation

Onboarding & Credentials

Two prerequisites gate a merchant’s first real sale. They are sequential, and both sit with the tax administration.

1. Declare every business unit through DIS+

Section titled “1. Declare every business unit through DIS+”

An evidenční jednotka (business unit) is a business premises — or, per § 4 of the Act, a website, part of a website, or an app, so e-commerce sellers need one too. On registration the authority assigns the id_jednotky; it cannot be chosen or substituted. Units must be declared before the certificate is issued, and changes must be reported within 15 days.

2. Obtain a cash certificate

Section titled “2. Obtain a cash certificate”

Certificates are issued only after the unit declaration. They are bound to the taxpayer’s EIČ, unlimited in number, and currently valid for one year. A key-length migration away from RSA-2048 is already announced (around 2030, or sooner at renewal), so nothing should assume a fixed key size or lifetime.

The taxpayer identifier

Section titled “The taxpayer identifier”

The EET identifier (EIČ) is the DIČ — the general Czech tax identification number, not the VAT number; a non-VAT-registered sole trader has one too. Fallbacks exist for taxpayers with no DIČ (CZ plus birth number, or a DIS+-issued identifier). There is no separate EET registration.

In fiskaly terms

Section titled “In fiskaly terms”
  1. Create the taxpayer with a CZ fiscalization (tax_id_number = DIČ).
  2. Commission one Location per declared unit — its label carries the DIS+-allocated id_jednotky, zero-padded to 14 digits.
  3. Commission one System per till — its label carries the chosen id_pokl.

The identifiers are validated for well-formedness at commissioning. The format check does not verify the value against DIS+ — a well-formed but wrong id_jednotky is still accepted by the authority and flagged only with warning code 6. Enter the DIS+-allocated number exactly.