Fluent in Finance, created by Bartle Bogle Hegarty, replaced Barclays' controversial Big campaign, starring Sir Anthony Hopkins, two years ago.
BBH has yet to decide on a replacement for Jackson, who starred in Pulp Fiction and Die Hard 3.
John O'Keeffe, the BBH executive creative director, said: "We have used Samuel for a couple of years, but my inclination is that the remaining ads in this campaign will be his last. Samuel has never been the idea, he's always been the vehicle for the idea and, although I'd never rule it out, I don't think we'll go back to using him in the ads."
O'Keeffe added that the next tranche of ads will have the same "tonal values" as the current campaign.
The first set of Fluent in Finance ads featured Jackson delivering complex monologues straight to camera, but later ads toned this down.
Earlier this year, the campaign won a gold Lion at the Cannes Advertising Festival.