The Members are the owners of the Association. They comprise an exceptional list of leading commercial banks located in the countries where major companies are headquartered or have their financial management offices: these companies are the main clients for the IBOS service.

The Members carry the main sales effort towards clients, and also are the main providers of services to the clients referred to them by other IBOS banks.

As providers of services they have advantages over branches of foreign banks.

Major commercial banks usually have nationwide coverage of their own country, are full members of all local clearings, and can offer relationship management in a number of ways to the customer: via a branch, via a commercial banking centre, via a telephone service, though electronic banking, or a combination at the election of the client and as fits their needs and organisation.

There is also a type of Member of IBOS known as a Limited Member. This type of Member acts for the time being only as Host Bank, introducing its clients to other Members and Associates.