There are two types of exemptions under GST:

Basic Exemption: If you are supplying goods and/or services below Rs.20 Lakh of value in the country and are not selling outside your state .
You are exempt from GST if you are supplying goods and/or services below Rs.10 Lakh of value  in the state of Jammu & Kashmir (J&k), Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, Himachal Pradesh and Uttrakhand.

Composition Levy: If your business turnover is less than Rs.75 Lakh per annum and you are not selling outside your state, you may apply for the composition levy - an exemption made for small businesses. Under this levy, a taxpayer shall pay tax as a percentage of his turnover in a state during the year without the benefit of input tax credit (ITC). The rate of tax for CGST and SGST/UTGST shall not be less than 1 percent for manufacturers and 0.5 percent in other cases; 2.5 percent (restaurants). No input tax credit is available here.

Five categories of registered persons are not eligible for the composition scheme:
  1. Supplier of services other than supplier of restaurant service
  2. Supplier of goods that are not taxable under the CGST/SGST/UTGST Act
  3. An interstate supplier of goods
  4. Person supplying goods through an electronic commerce operator
  5. Manufacturer of certain notified goods