San Marino IBAN validator
How the IBAN format works
- Format
- SM + 2 check digits + 1 CIN letter + 5-digit bank code + 5-digit branch code + 12-char account number (27 chars)
- Example
- SM86U0322509800000000270100
Things to watch for
- 27 characters total
- Checks structure and checksum only, not that the account exists
^SM[0-9]{2}[A-Z][0-9]{5}[0-9]{5}[0-9A-Z]{12}$A San Marino IBAN is 27 characters: “SM”, two check digits, a single CIN check letter, a 5-digit ABI bank code, a 5-digit CAB branch code, and a 12-character account number. San Marino is a fully independent microstate wrapped inside Italy, and while it isn’t in the EU, its banks settle payments through Italian clearing rails — so its IBAN borrows Italy’s exact internal structure (CIN, ABI, CAB) and simply swaps the country prefix to “SM”. Anyone paying a San Marino business or converting an older domestic account number needs those three blocks — CIN, ABI, CAB — in the right order, since the layout is easy to confuse with a plain Italian IBAN at a glance.
How this validator works
The tool checks for the “SM” prefix, confirms a single letter sits in the CIN position immediately after the check digits, confirms the ABI block is 5 digits and the CAB block is 5 digits, and confirms the account number is 12 alphanumeric characters — then runs the real mod-97 (ISO 7064) checksum, entirely in your browser with nothing sent to a server.
What a pass doesn’t tell you
A pass confirms the 27 characters are correctly formed and pass the IBAN-level checksum — it isn’t a separate recomputation of Italy’s domestic CIN formula, and it doesn’t resolve the ABI or CAB to an actual bank or branch name. This tool never contacts a bank in San Marino or Italy. If a San Marino IBAN fails, check first whether the CIN letter got merged into the ABI block by mistake — that boundary is the single most common source of copy-paste errors in this format.
Scope: structure and mod-97 checksum validation for San Marino IBANs only — not bank-name lookup, payment processing, or confirming an account is active. Catch the typo here; confirm the account through the bank itself.
Content last reviewed 2026-07-09.
IBAN FAQ
What does a San Marino IBAN look like?
27 characters: 'SM', two check digits, a single CIN check letter, a 5-digit ABI bank code, a 5-digit CAB branch code, and a 12-character account number — for example SM86U0322509800000000270100. That's the same internal layout Italy uses, just with 'SM' in place of 'IT'.
Why does a San Marino IBAN use ABI and CAB codes like Italy's?
San Marino isn't part of the EU or Italy, but its retail banks clear payments through Italy's banking system, so it adopted the same domestic building blocks — the CIN letter, ABI bank code, and CAB branch code — inside its own 'SM' IBAN rather than inventing a separate numbering scheme.
Does this tool separately verify the CIN letter's own formula?
No. It checks that a CIN-shaped single letter, a 5-digit ABI, a 5-digit CAB, and a 12-character account number are all present in the right positions, then runs the IBAN's own mod-97 checksum. It doesn't recompute Italy's separate domestic CIN algorithm as an additional check.