Finance
Understanding IBAN: Structure, Country Formats & The Mod-97 Checksum
Just ask and get Editorial Team(Banking Systems & Cybersecurity)
Updated 2026-09-20
7 min read
Key Takeaway:A technical breakdown of international banking standards, account identifiers, and mathematical error-detection algorithms.
The Structure of an IBAN
An IBAN consists of up to 34 alphanumeric characters:
- Characters 1–2: Two-letter ISO country code (e.g. GB, DE, FR)
- Characters 3–4: Two-digit check number calculated via Mod-97
- Characters 5+: Basic Bank Account Number (BBAN) containing bank, branch, and account codes.
Frequently Asked Questions
Does the United States use IBANs?
No, US banks utilize 9-digit ABA routing numbers and account numbers domestically, and SWIFT/BIC codes for incoming international transfers.