Spanish IBAN Format (ES): Structure, Domestic Check Digits, and Examples

The Spanish IBAN is 24 characters long and incorporates a two-digit domestic check digit pair that predates the IBAN standard. Spain uses the IBAN for all SEPA payments, and Spanish IBANs are frequently processed by businesses trading with the Iberian market. The unique embedded check pair inside the BBAN is the feature most likely to trip up systems built for German or UK IBANs.

Spanish IBAN at a Glance

• Country code: ES
• Total length: 24 characters (always)
• Format: ESkk bbbb ssss DDcc cccccccccc
• BBAN length: 20 digits
• Character types: digits only after the country code

Spanish IBAN Structure Explained

1. Country Code, ES (2 characters)

The ISO 3166-1 alpha-2 code for Spain. Every Spanish IBAN begins with ES.

2. Check Digits, kk (2 digits)

Two decimal digits computed with the MOD-97 algorithm, standard across all IBANs.

3. Bank Code, bbbb (4 digits)

A 4-digit entidad (entity) code identifying the bank. Assigned by the Banco de España. Examples:

• 2100, CaixaBank
• 0049, Santander
• 0182, BBVA

4. Branch Code, ssss (4 digits)

A 4-digit oficina (branch/office) code that identifies the specific branch where the account was opened.

5. Domestic Check Digits, DD (2 digits)

Two domestic check digits unique to Spanish IBANs, calculated using a modulo-11 algorithm over the bank code, branch code, and account number. These are separate from the IBAN check digits at positions 3–4 and serve as an additional internal integrity check.

6. Account Number, cccccccccc (10 digits)

The 10-digit account number (número de cuenta) identifying the individual account at that branch. Spanish account numbers are always exactly 10 digits; no padding is required for modern accounts.

Spanish IBAN Example Explained

ES91 2100 0418 4502 0005 1332

• Country: ES
• Check digits: 91
• Bank code: 2100 (CaixaBank)
• Branch code: 0418
• Domestic check digits: 45
• Account number: 0200051332

Second Example, Santander

ES74 0049 0001 5521 0001 3030

• Country: ES
• Check digits: 74
• Bank code: 0049 (Santander)
• Branch code: 0001
• Domestic check digits: 55
• Account number: 2100013030

How Spanish IBAN Validation Works

1. Country code check: First two characters must be exactly ES.
2. Length check: Total character count (spaces removed) must be exactly 24.
3. Character type check: Positions 3–24 must all be decimal digits. No letters appear in a Spanish IBAN beyond the country code.
4. MOD-97 check: Move the first four characters to the end, convert letters to numbers, compute modulo 97. Result must equal 1.

The ibanchecker.cash validator runs all four checks and displays the bank code, branch, domestic check digits, and account number as separate fields.

Common Spanish IBAN Mistakes

Ignoring the Domestic Check Digits

The two domestic check digits at positions 13–14 of the IBAN are sometimes confused with the IBAN check digits (positions 3–4). They are computed differently and serve a different purpose. Systems that attempt to reconstruct a Spanish IBAN from raw bank code + branch + account number must also compute these domestic digits correctly, or the resulting IBAN will be invalid.

Wrong Length

Spanish IBANs are 24 characters, shorter than French or Italian IBANs, which are both 27. Copying a French IBAN template and expecting the same length will produce errors.

Spaces in Electronic Transmission

Remove all spaces before API calls or payment file submission: ES9121000418450200051332.

Spanish IBAN and SEPA

Spain is a full SEPA member. All Spanish bank accounts accept SEPA Credit Transfers and SEPA Direct Debits across the 36-country zone. For payments outside SEPA, the bank's BIC code is required alongside the IBAN. Look up any Spanish bank's BIC using the ibanchecker.cash SWIFT directory.

Validating Spanish IBANs in Bulk

Finance teams processing Iberian supplier payments can validate multiple IBANs at once using the ibanchecker.cash bulk checker. Upload a CSV or paste up to 100 IBANs and receive per-row bank code, branch, and validation results.

Sources & References

• SWIFT IBAN Registry — Official IBAN country format specifications
• ISO 13616 — International standard for IBAN
• EPC SEPA Participants — SEPA scheme participants register
• Banco de España — Spanish central bank and authority for entidad (bank code) assignments
• ECB TARGET2 — Eurozone payment system operated by the European Central Bank

Last updated: June 2026