In 5GS, Single-Network Slice Selection Assistance Information (S-NSSAI) based backoff (BO) timers (T3585) can be applied to either 3GPP access or non-3GPP access or both access based on a 5GSM congestion re-attempt indicator. When UE receives a 5GSM message over a specific access, UE needs to handle a current running timer. In one novel aspect, it is proposed that the UE stops the running timer applied for the same access which the message is received, and also stops the running timer applied for both access types. In another novel aspect, it is proposed that the UE stops the running timer applied for the access different from the access which the message is received when the UE starts a new timer applied for both access types.