You can update your client's mobile number and email address in their GST profile by amending non-core fields. Navigate to Registration > Amendment > Non-core field > Primary authorised signatory. Here, you can edit and replace your details with your client's, requiring a different OTP for verification. The approval for this change is typically same-day.
22 January 2021
Go to Registration- amendment Non-core field- Primary authorized signatory- edit- delete mail/mobile and insert new mail/mobile-different OTP will come - feed and submit the form. same day approval will get