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What Is an IBAN?
An International Bank Account Number (IBAN) is a standardized format for identifying bank accounts across borders. Introduced to simplify international payments, IBANs are now mandatory for SEPA transfers within Europe and accepted in over 80 countries worldwide.
An IBAN consists of a two-letter country code, a two-digit check number, and a Basic Bank Account Number (BBAN) that varies in length and format by country. The total length ranges from 15 characters (Norway) to 34 characters (Malta).
How IBAN Validation Works
Validating an IBAN involves three distinct steps that together confirm both the format and mathematical integrity of the number.
- Country code check — verifies the two-letter ISO 3166-1 country code is valid and supported
- Length check — confirms the total character count matches the expected length for that country
- Checksum validation — performs the MOD-97 algorithm to verify the check digits are mathematically correct
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Validate an IBAN →When To Use IBAN Validation
IBAN validation is essential anywhere bank account numbers are collected or processed. Catching errors before submission prevents costly payment failures.
- Payment forms — validate IBANs at input to prevent failed transfers and customer frustration
- Supplier onboarding — verify bank details before processing invoices or setting up payment runs
- Data migration — clean legacy account number data when migrating to SEPA-compliant systems
Frequently Asked Questions
Does a valid IBAN guarantee the account exists?
No. IBAN validation confirms the format and check digits are correct, but cannot verify the account is open and active. For that, a small test transfer or bank API verification is required.
Are IBANs used outside Europe?
Yes, IBANs are used in over 80 countries including parts of the Middle East, North Africa, and some Caribbean nations. However, the US, Canada, Australia, and most of Asia use different account number formats.
What is the MOD-97 check and why does it matter?
MOD-97 is the mathematical algorithm used to generate and verify IBAN check digits. It catches around 97% of single-digit errors and transpositions, making it highly effective at detecting the most common data-entry mistakes.