An operation method of a terminal in a communication system may comprise receiving a downlink data channel from a base station in a slot #n or a slot #(n−l); receiving a slot format indicator (SFI) indicating a format of a slot #(n+k) in which an uplink control information (UCI) is to be transmitted, from the base station in the slot #n; and transmitting the UCI including a hybrid automatic repeat request (HARQ) response for the downlink data channel to the base station in the slot #(n+k). Here, each of n and k may be an integer equal to or greater than 0, and l may be an integer equal to or greater than 1.