Is gst registration mandatory in case a person is exporting herbs which are exempted in GST and aggregate turnover is around 45 Lakhs? What will be the position of law regarding registration if turnover is below 40 lakhs? The person is not engaged in any other activities other than export of herbs. Will section 24 regarding compulsory registration override section 23 regarding cases where registration is not required?

Reply— Under section 22(1) Every supplier shall be liable to be registered under this Act in the State or Union territory, other than special category States, from where he makes a taxable supply of goods or services or both, if his aggregate turnover in a financial year exceeds twenty lakh rupees.

However, as per section 24 of CGST Act Notwithstanding anything contained in sub-section (1) of section 22,  persons making any inter-state taxable supply are required compulsory registration under section 24 of the Act. Export of goods is also covered under inter-state supply.

Therefore, registration is not required because you are supplying exempted goods and not taxable goods and section 24 is regarding taxable supply. 

Threshold limit of 40 lakhs will not applicable in this case.