One disclosure of the present specification provides a method by which a session management function (SMF) supports quality of service (QoS). The method can comprise the steps of: determining, on the basis of a QoS flow not being a guaranteed bit rate (GBR) QoS flow in a multi-access (MA) protocol data unit (PDU) session, that a QoS profile is transmitted to both a third generation partnership project (3GPP) access and a non-3GPP access; determining, on the basis of the QoS flow being the GBR QoS flow in the MA PDU session, that the QoS profile is transmitted to only one of the 3GPP access and the non-3GPP access; and transmitting the QoS profile on the basis of the determinations.