The bank's DM and online direct response account has been held by Grand Union since late last year. The agency was handed the business after winning a pitch for Abbey's £7 million digital account.
It is unclear whether the Cahoot and Abbey.com managing director, John Goddard, will hold a pitch for the business or hand it straight to a DM specialist.
Cahoot's marketing efforts have been conspicuous by their absence since Abbey was taken over by Spain's Banco Santander Central Hispano in November 2004.
The decision to move the account is understood to herald a renewed focus on DM. The online bank is planning to launch a range of new services as part of a change in strategy to offer simpler products and better rates.
There has also been speculation that Banco Santander will drop the Cahoot brand. In February, Abbey merged Cahoot's management into the same department as Abbey, but insisted the brands would continue to be run separately.