UK IBAN Format, Length and United Kingdom Example

The relationship between a UK IBAN and domestic details

The United Kingdom uses a 22-character IBAN beginning with GB, not UK. The Swift IBAN Registry describes its 18-character BBAN as a four-letter bank identifier, a six-digit branch identifier corresponding to the domestic routing block, and an eight-digit account number. All three parts are included in the international value. A domestic sort code and account number shown separately on a UK invoice are not, by themselves, a complete IBAN, and the four bank letters must not be removed.

When a form specifically asks for an IBAN, use the complete GB value rather than constructing one from domestic details. Remove print spaces only, keep leading zeroes in the six- and eight-digit blocks, and confirm the final digital value has 22 characters. Common errors include entering UK as the country prefix, pasting only the domestic account number, or treating the four-letter bank identifier as a BIC. MOD97-10 can review the supplied international value but cannot generate authoritative payment instructions from partial fields.

The Registry notes technical country-code coverage that includes the Isle of Man, Jersey, and Guernsey, while provider rules and payment routes can still differ. BankCodeKit does not check a UK bank directory, Faster Payments, CHAPS, Swift connectivity, or account ownership. Review a BIC separately if the provider requests one. Before relying on changed invoice details, confirm the beneficiary and transfer requirements with the recipient or bank through a known channel. A format pass does not establish that the account is reachable or appropriate for the intended payment.

How domestic UK fields appear in international form

• The value starts with GB, the IBAN country code for the United Kingdom.
• The next two characters are international check digits.
• For the United Kingdom, the remaining 18 characters form the country-specific BBAN section: 18 BBAN characters after the country code and check digits.
• UK IBANs use the GB country code and include a BBAN section that is different from a domestic UK sort code plus account number display.
• The NWBK letters in the example are part of the IBAN value and remain present in digital format.

Keeping NWBK and the sort code in place

Compare the grouped invoice-style value used for the United Kingdom with the compact GB input produced after presentation spaces are removed.

Input shown on page

GB29 NWBK 6016 1331 9268 19

Normalized digital value

GB29NWBK60161331926819

Expected length

22 characters

Result interpretation

A passing GB result means the visible value matched supported British structure and MOD97 rules, not that the account or payee was verified.

What the local GB format check evaluates

• Whether the IBAN starts with the GB country code.
• Whether the IBAN has 22 characters after normalization.
• Whether the value uses allowed letters and digits.
• Whether the MOD97-10 checksum is valid.

What a GB format pass cannot establish

• Whether the account exists.
• Whether it belongs to the named payee.
• Whether the bank or account can receive the intended payment.

Review UK account and institution codes separately

• Check this GB IBAN locally for country, length, characters, and MOD97 result only.
• Review United Kingdom's SEPA country entry as reference context, not bank or account readiness.
• Compare the IBAN with a separate BIC/SWIFT code when a British invoice includes both values.

Using only an account number when an IBAN is requested

• Using only a domestic UK account number where an international IBAN is required.
• Removing the bank-code letters from the GB IBAN before checking the format.

United Kingdom country scope in SEPA data

For the United Kingdom, the local SEPA country reference is: SEPA country - Non-EEA. The GB entry provides geographical scope only; participation by a particular British bank or account must be confirmed separately.

Non-EU/EEA SEPA country. SEPA participation does not mean EU or EEA payment rules apply.

Choosing between UK domestic and IBAN references

• Comparing the 22-character GB format with a payment form that asks for international rather than domestic UK details.
• Checking whether an international payment form is asking for an IBAN rather than only UK domestic account details.
• Use the IBAN Checker after this country reference for the United Kingdom when you need a local MOD97 result for one GB value.

Questions about GB, sort codes, and BIC requirements

Reference data reviewed: 2026-08-15 Next scheduled data review: 2026-10-17 Sources: Swift IBAN Registry, European Payments Council SEPA scheme countries list, Pay.UK - Format of the IBAN issued in the UK Reference data is reviewed periodically. BankCodeKit does not perform live bank, account, sanctions, or payment-network confirmation.