As per Section 9(3) R/w Notification 13/2017 Ct rate Insurance Commsion is Under RCM ,as it is supply on which tax is paid by recipient but since Mutual Fund Commission is Taxable Supply so you cannot enjoy the provsion of Section 23 (Not required to registered if Exclusively supplied exempted services) Thus as per Section 22 you are liable obtain registration.
But aggrregate turnover defination excludes inward supplies on which tax is payable by a person on reverse charge basis. so will insurance commission will be included for the threshhold limit