Application for GST no by Mutual fund agent

I am 65 old Indian Male resident. Mine income from MF agency is less than 20 lakhs. since I am not having GST no MF house deducts 18% as GST on RCM basis. To avoid such deduction by MF house, I wish to opt GST no voluntarily. so should I charge GST to MF house on commission to be charged ? Or since my income is less than 20 lakhs I should not charge GST ? what is advisable ?