Disclosed is a method performed by a user equipment (UE) in a communication system, including receiving, from a base station, downlink control information including resource assignment information of a physical downlink shared channel (PDSCH), identifying a number of resource elements (REs) for the PDSCH based on the resource assignment information of the PDSCH, identifying a temporary transport block size (TBS) based on the number of REs for the PDSCH, identifying a TBS based on the temporary TBS, and receiving, from the base station, the PDSCH based on the TBS, wherein the number of REs for the PDSCH is identified by excluding a number of REs associated with a channel state information reference signal (CSI-RS) and a control channel.