According to a scene which did not make it into the broadcast version of the episode, Starfleet Accounting received the bill when Starfleet officers ordered food or drinks at Quark's. In the scene, Miles O'Brien complained to Quark that Starfleet Accounting had been all over him for ordering six cases of Champagne for the night shift, the implication being that Quark was billing O'Brien for stuff he didn't order. (Star Trek: Deep Space Nine Companion - A Series Guide and Script Library)