Method for processing a set of at least one sheet in a sheet processing apparatus comprising the steps of - determining a lateral delivery position for the set of at least one sheet (20', 30, 40); - moving a post-processing module (25, 33, 43) with respect to the set of at least one sheet (20', 30, 40) to an operating position such that the post-processing module (25, 33, 43) is able to operate at a predetermined position on the set of at least one sheet (20', 30, 40); - operating the post-processing module (25, 33, 43) to subsequently a) engage the set of at least one sheet (20', 30, 40) to process the set of at least one sheet (20', 30, 40) into a processed set of at least one sheet; b) move the post-processing module (25, 33, 43) from the operating position to the lateral delivery position in coupling engagement with the processed set of at least one sheet, such that the processed set of at least one sheet is moved to the lateral delivery position; c) disengage the post-processing module (25, 33, 43) to deliver the processed set of at least one sheet at the lateral delivery position, wherein the coupling engagement during the lateral movement of the post-processing module (25, 33, 43) and the processed set of at least one sheet comprises an at least partially protruding engagement. - determining a lateral delivery position for the set of at least one sheet (20', 30, 40); - moving a post-processing module (25, 33, 43) with respect to the set of at least one sheet (20', 30, 40) to an operating position such that the post-processing module (25, 33, 43) is able to operate at a predetermined position on the set of at least one sheet (20', 30, 40); - operating the post-processing module (25, 33, 43) to subsequently a) engage the set of at least one sheet (20', 30, 40) to process the set of at least one sheet (20', 30, 40) into a processed set of at least one sheet; b) move the post-processing module (25, 33, 43) from the operating position to the lateral delivery position in coupling engagement with the processed set of at least one sheet, such that the processed set of at least one sheet is moved to the lateral delivery position; c) disengage the post-processing module (25, 33, 43) to deliver the processed set of at least one sheet at the lateral delivery position, wherein the coupling engagement during the lateral movement of the post-processing module (25, 33, 43) and the processed set of at least one sheet comprises an at least partially protruding engagement. a) engage the set of at least one sheet (20', 30, 40) to process the set of at least one sheet (20', 30, 40) into a processed set of at least one sheet; b) move the post-processing module (25, 33, 43) from the operating position to the lateral delivery position in coupling engagement with the processed set of at least one sheet, such that the processed set of at least one sheet is moved to the lateral delivery position; c) disengage the post-processing module (25, 33, 43) to deliver the processed set of at least one sheet at the lateral delivery position, wherein the coupling engagement during the lateral movement of the post-processing module (25, 33, 43) and the processed set of at least one sheet comprises an at least partially protruding engagement.