A building society roll number is an alphanumeric reference code used to identify individual building society accounts. It is a reference code with letters and numbers that is issued by building societies to every account holder. Whilst most standard UK bank accounts have an 8 digit account number and 6 digit sort code, some Building Society accounts may also have a roll number. Roll numbers are usually up to 18 characters long. If you are making a payment to a Building Society account, then the Building Society should provide you with the roll number if required. When making a payment online, you must add the roll number as the reference of the payment you are sending. It is important to note that if you are required to provide your roll number when you are making a payment to a building society account, you must not type any additional characters in the payment reference. To find your building society roll number, you can check your statements or any original documentation provided by the institution when you signed up. You can also contact your building society directly, but only the account holder can do this.