The Basic Bank Account Number (BBAN) is the domestic account number format used before IBAN standardization. It includes:

• Bank code
• Branch code (where applicable)
• Account number

BBAN characteristics:

• Country-specific format
• Varies in length by country
• Forms part of the IBAN

The BBAN is the foundation of the IBAN, with the country code and check digits added to create the international format.