Following persons are not allowed to opt for the composition scheme:
a) a casual taxable person or a non-resident taxable person;
b) suppliers whose aggregate turnover in the preceding financial year crossed Rs. 75 lakhs;
c) supplier who has purchased any goods or servcies from unregistered supplier unless he has paid GST on such goods or services on reverse charge basis;
d) supplier of services, other than restaurant service;
e) persons supplying goods which are not taxable under GST law;
f) persons making any inter-State outward supplies of goods;
g) suppliers making any supply of goods through an electronic commerce operator who is required to collect tax at sourceunder section 52; and
h) a manufacturer of following goods:
1.Ice cream and other edible ice, whether or not containing cocoa 2.Pan masala 3.Tobacco and manufactured tobacco substitutes.
(FAQ 4: COMPOSITION LEVY)