IBAN Checker & Validator

How IBAN validation works

An IBAN (International Bank Account Number, ISO 13616) always starts with a two-letter country code and two check digits, followed by the national account structure (BBAN). The check digits are computed with the MOD-97-10 algorithm: move the first four characters to the end, replace every letter with its number (A=10 … Z=35), and the resulting big number modulo 97 must equal 1. A single mistyped digit or a swapped pair of characters almost always breaks this test — that is exactly what this checker catches before a payment bounces.

What this tool checks

• Country code is a real IBAN country and the length matches that country's registered format
• MOD-97 checksum passes (catches typos and transposed characters)
• Structure breakdown: bank identifier, sort code / branch (where the national format defines one), account number

What it cannot check

No public, free service can confirm that an account is open or who owns it — that data sits with the account-holding bank. For UK payments use Confirmation of Payee; for SEPA, the Verification of Payee scheme is rolling out across the EU. Treat a valid checksum as "safe to submit", not "verified recipient".

A worked example of the MOD-97 check

Take GB29 NWBK 6016 1331 9268 19. Move the first four characters to the end: NWBK60161331926819GB29. Replace each letter with its number (N=23, W=32, B=11, K=20, G=16, B=11): 23321120…161129. Divide that number by 97. The remainder is 1, so the IBAN is valid. Any single mistyped character changes the remainder and fails the test.

IBAN length by country

Every country registers a fixed IBAN length with SWIFT. A different length is an immediate error, which is the first thing this checker tests:

The checker validates the registered length for all 84 IBAN countries, including those not listed above.

IBAN vs. sort code, account number and BIC

For a UK business these four identifiers overlap, which causes constant confusion:

• Sort code and account number identify a UK account for domestic payments over BACS, Faster Payments and CHAPS. They are all you need inside the UK.
• IBAN wraps the same national account details in an international format with a country code and checksum. It is required for SEPA payments and used widely for other cross-border transfers.
• BIC (SWIFT code) identifies the bank, not the account. Some corridors still require it alongside the IBAN — see our SWIFT guide.

Note that the United States, Canada and Australia do not use IBANs at all. Payments there use routing numbers (ABA), transit numbers or BSB codes together with the account number.

Frequently asked questions

Does a valid checksum mean the account exists?

No. The MOD-97 check confirms the IBAN is structurally correct and free of typos, which catches the vast majority of input errors. It cannot confirm that the account is open or belongs to your intended payee. For that, use your bank's Confirmation of Payee check.

Is my IBAN sent to a server?

No. Validation runs entirely in your browser using the published ISO 13616 algorithm. The IBAN you enter never leaves your device.

Why does my payment fail even though the IBAN is valid?

Common causes: the account is closed, the beneficiary name does not match under Confirmation of Payee, the currency or payment rail is not supported by the receiving bank, or the accompanying BIC is wrong. A valid IBAN is necessary but not sufficient.

Can a company refuse my IBAN because it is from another country?

Within the Single Euro Payments Area, no. Article 9 of EU Regulation 260/2012 prohibits "IBAN discrimination" — a business or employer in the SEPA area cannot insist on a domestic IBAN for euro payments. This matters particularly for payroll providers paying employees across several countries.

What is Confirmation of Payee?

Confirmation of Payee (CoP) is the UK scheme that checks whether the account name you enter matches the name on the receiving account, before the payment leaves. An equivalent scheme, Verification of Payee, applies to euro payments in the SEPA area. Neither is part of the IBAN itself — they are separate checks run by your bank.

Related tools and guides

Working out what a transfer will cost? Use the payment cost calculator or compare FX margins with the FX calculator. Converting a foreign invoice for a VAT return needs the official HMRC monthly exchange rates. For background on how cross-border payments are routed, see our cross-border payments guide, and for dedicated and virtual account numbers, IBAN services.

Compiled by the financeb2b editorial team · Validation follows ISO 13616 · Last updated 29 August 2026 · Editorial policy