Embodiments of the present disclosure relate to frequency or RAT selection based on slice availability. In one aspect, a core network function is provided for determining information for RAT and/or frequency selection based on knowledge of network slices and providing that information to a RAN node, which may provide that information to a UE. The information may be a RFSP index or other index parameter, which may be set based on subscription related information or other information. Slice knowledge may include knowledge of availability of network slices at the network, active slices for the UE, slices to which the UE is registered or connected, and/or slices to which the UE is allowed access. In another aspect, a RAN node performs mapping to mobility policies for UE active or idle mobility based on the determined information along with slice or subscription information provided by a CN node.