Methods and apparatuses for a (re)selection of candidate carriers for transmission in SL CA in a wireless communication system. A method of operating a UE includes: receiving, from a peer UE, an RSRP; identifying information including a first threshold and a second threshold for a sidelink (SL) transmission; determining whether multiple SL carriers are available for the SL transmission; measuring, based on a determination that the multiple SL carriers are available, a CBR; and selecting a SL carrier from the multiple SL carriers for the SL transmission when the measured CBR is less than the first threshold and the received RSRP is greater than the second threshold.