Certain aspects of the present disclosure provide techniques for communicating user data in a small data transfer (SDT) in a non-terrestrial network (NTN) while a user equipment (UE) is in an idle or inactive mode. A method that may be performed the UE includes transmitting, to a non-terrestrial base station (NTBS) in an NTN, an SDT indication message including a first indication that the UE has user data to transmit in an SDT while the UE is in an idle or inactive mode, receiving, from the NTBS in response to the SDT indication message, a resource indication message including an indication of a set of resources for transmitting user data in the SDT, and transmitting the user data in the SDT to the NTBS while the UE is in the idle or inactive mode via the set of resources indicated in the resource indication message.