Methods, systems, and devices for wireless communication are described. A user equipment (UE) configured with several component carriers (CCs) may select one or more CCs for fast activation. The UE may, in various examples, autonomously select the CCs for fast activation or may receive signaling indicating such CCs. In some cases, the UE may place the selected CCs in a semi-active state by detecting and synchronizing the CCs while refraining from control channel monitoring. In other examples, the UE may identify a set of CCs that may be activated quickly based on channel conditions or that have activation interdependency, such as CCs in a physical uplink control channel (PUCCH) group. The UE may then trigger an activation for one of the selected CCs, determine it is capable of fast activation, and begin monitoring, e.g., for control information, after a reduced delay period based on the fast activation.