The business is split between Carat, which handles press buying, Latitude, which handles online buying and MediaVest Manchester, which handles TV buying.
The review covers all media, including directories advertising, door-to-door and paid search. Non-roster agencies have also been invited to pitch for the business.
The bank last reviewed its media in 2004 and retained MediaVest Manchester, while adding Carat to the roster. Creative duties are split between McCann Erickson and Big Communications.
Alliance & Leicester said the review is likely to be concluded in October, with the new arrangements in place by the start of next year.
Lesley Vernon, the head of marketing communications at Alliance & Leicester, said: "We are happy with our current media buying arrangements. However, in the spirit of continuous improvement, we regularly review every aspect of our business to ensure we are using our resources in the best possible way. As part of this we feel it is the right time to review our existing media buying arrangements."