Czechia IBAN validator

A Czech IBAN is 24 characters, entirely numeric after the country code: “CZ”, two check digits, a 4-digit bank code, a 6-digit account prefix, and a 10-digit account number. The account-prefix block is a specifically Czech (and Slovak) feature — a segment that qualifies the account number further and is present even when its value is all zeros, so don’t drop it or assume it’s padding you can omit. Anyone paying a Czech supplier, landlord, or employer via SEPA, or entering an IBAN into a form that no longer accepts a domestic account number and bank code separately, needs all 24 digits in the right blocks.

How this validator works

This tool checks the “CZ” prefix, confirms the bank code block is 4 digits, the account prefix block is 6 digits, and the account number block is 10 digits, then runs the mod-97 checksum (ISO 7064) Czech banks use to generate a valid IBAN — entirely in your browser, with no signup and nothing sent to a server. The result shows the moment you stop typing.

What a pass doesn’t tell you

A pass confirms the IBAN is correctly formed and internally consistent — not that the account is open, active, or belongs to whoever you expect. This tool doesn’t resolve the bank code to an institution name and never contacts a bank or clearing system. If a Czech IBAN fails, check first whether the 6-digit account-prefix block was accidentally merged into or dropped from the 10-digit account number — that boundary is the detail most often mistyped.

Scope: Czech IBAN structure and mod-97 checksum validation only — not SEPA payment processing, bank-name lookup, or confirming an account is active, none of which a client-side check can tell you. Use this validator to catch a typo before a transfer fails; use your bank to confirm the account itself.

Content last reviewed 2026-07-07.