As per Section 22 of the CGST/SGST Act 2017, every supplier (including his agent) who makes a taxable supply i.e. supply of goods and / or services which are leviable to tax under GST law, and his aggregate turn over in a financial year exceeds the threshold limit of twenty lakh rupees shall be liable to register himself in the State or the Union territory of Delhi or Puducherry from where he makes the taxable supply.
In case of four special category States (Manipur, Mizoram, Nagaland & Tripura), this threshold limit for registration liability is ten lakh rupees.
Besides, Section 24 of the Act mentions certain categories of suppliers, who shall be liable to take registration even if their aggregate turnover is below the said threshold limit of 20 lakh rupees.
On the other hand, as per Section 23 of the Act, an agriculturist in respect of supply of his agricultural produce as also any person exclusively making supply of non-taxable or wholly exempted goods and/or services under GST law will not be liable for registration.