The Building Societies Association (BSA) is the trade body that represents all building societies and several large credit unions in the United Kingdom. It was established in 1869 under the original name Building Societies Protection Association, with the aim of coordinating a collective response to proposed government changes that threatened stamp duty exemptions for mutual lenders.[1]
As of 2024, the BSA represents 49 member institutions, comprising 42 building societies and 7 credit unions, which together serve approximately c. 26 million customers across the UK.[2]
The association advocates on behalf of its members in relation to financial services regulation, legislation, and policy developments in both the UK and Europe. It also provides research, public affairs support, and guidance for the mutual sector, with a focus on ensuring a sustainable and competitive environment for member institutions.
As of September 2024, UK building societies and their subsidiaries collectively held total assets amounting to approximately £525 billion. Their residential mortgage balances stood at over £395 billion, representing around 24% of the total outstanding mortgage balances in the United Kingdom.[3]
In terms of savings, building societies held approximately £399 billion in retail deposits, accounting for about 19% of all such deposits in the UK. They also managed £153.9 billion in cash ISAs, around 40% of the total UK balance.[4]
The building society sector collectively employed around 52,300 full and part-time staff and operated through approximately 1,300 branches, making up around 30% of the UK's total bank and building society branch network.[5]
Among these institutions, the Nationwide Building Society is the largest. As of April 2024, it reported total assets of £271.9 billion, employed approximately 17,680 people, and operated 605 branches across the United Kingdom — more than any other UK banking brand.[6]
The Building Societies Association (BSA) represents UK-based mutual lenders and deposit takers, including all 42 building societies and seven credit unions. It also encompasses certain subsidiaries and trading names of building societies. For instance, Virgin Money UK plc became a wholly owned subsidiary of Nationwide Building Society following its acquisition on 1 October 2024. As of May 2025, the BSA comprises 49 members: 42 building societies and 7 credit unions.