Check an IBAN
Validate the IBAN
The checker removes whitespace and converts lowercase letters to uppercase. It compares the character count and national pattern with SWIFT’s IBAN registry.
The checksum test moves the first four characters to the end, converts letters to numbers from A = 10 to Z = 35 and divides by 97. A valid checksum leaves remainder 1. Check digits must be between 02 and 98.
The synthetic example GB20 NWBK 0000 0000 0000 00 passes the UK format and checksum. Changing its final character to 1 preserves the format but fails the checksum. These are demonstration identifiers, with no account or payment implied.
Read the Identifier Components
The first two letters identify the registered country format. The next two characters are check digits. The remaining characters form the Basic Bank Account Number, or BBAN.
For SWIFT’s UK example, GB29 NWBK 6016 1331 9268 19, the bank identifier code is NWBK and the branch code is 601613. The remaining eight digits are 31926819.
Bank and branch codes appear only where SWIFT publishes their positions. The checker does not map a code to a bank name or infer a branch where none is listed. Other national check digits and domestic account rules are outside this format test.
Keep the original identifier beside your checked version in an investigation record. A valid identifier can still point to the wrong recipient. Evidence of ownership requires separate records.
Use a Public Validation Method
The same syntax test applies to an IBAN shown on a bank statement or supplied through Wise. A provider’s name does not change the national format or checksum.
The bundled rules cover the 89 country prefixes in SWIFT’s IBAN registry, Release 103. Unsupported prefixes receive an explicit result instead of an invented country or account match.
A checksum failure is a reason to compare the entry with the original payment instructions. A passing checksum leaves the recipient and payment status unverified.
For an investigation spanning other asset types, read how identifier evidence fits into crypto tracing. Preserve the source records needed to connect an identifier with a person or transaction.