Tax Payment on Behalf of Client

I am a lawyer, recently started practice in tax laws, my clients are paying their tax from my account, there will be any complications for the same transactions.

or do I need do GST registration? but my actual receipts are less than 20 lakhs,

My total receipts 50 lakhs (including client tax)

Tax Paid 35 Lakhs 

remaining is my receipts and on which I have paid the income tax under presumptive scheme.

Thank you in advance for your help.