The company said that Abbey and Alliance & Leicester's current agency Carat and Bradford & Bingley's agency Mediacom North have been informed of the decision.
Carat is being invited to re-pitch for the account while a shortlist of agencies is also being developed with a remit to cover traditional and online media, including business-to-business and directories.
The review follows Santander's purchase of Alliance & Leicester and the savings book of Bradford & Bingley in October. Santander said it hoped to complete the review by the end of the year.
Keith Moor, Abbey's director of brand and communications, who will oversee the process, said ‘Carat has done a great job for Abbey and A&L over the past few years. However, with the acquisition of A&L and B&B, we need to consider our media planning and buying requirements across three businesses. In a tough economic environment, we are committed to ensuring we are getting real value from all our agencies.'