Can every taxable person opt to pay tax under composition scheme

No, the registered person whose aggregate turnover in the preceding financial year does not exceed seventy-five lakh rupees (subject to fifty lakh rupees in case of specified states as prescribed under Notification 08/2017-Central Tax, dated 28.06.2017), may opt to pay tax subject to satisfaction of the following conditions:
1. he is not engaged in the supply of services other than supplies referred to in clause (b) of paragraph 6 of Schedule II (Restaurant Services);
2. he is not engaged in making any supply of goods which are not leviable to tax under this Act (like petrol, diesel, alcohol liquor for human consumption, etc.);
3. he is not engaged in making any inter-State outward supplies of goods;
4. he is not engaged in making any supply of goods through an electronic
commerce operator who is required to collect tax at source under section 52; and
5. he is not a manufacturer of such goods as may be notified by the Government on the recommendations of the Council:
However, manufacturers of ice cream, pan masala, tobacco and tobacco substitutes are not eligible for composition scheme.

(ICAI FAQ PUBLICATIONS 06-09-2017 COMPOSITION LEVY: FAQ NO. 54)

What is the rate of tax applicable to a taxable person opting to pay tax under composition scheme

Section 10(1) of the CGST Act, 2017 prescribes, subject to such conditions and
restrictions as may be prescribed, that the rate of tax shall not exceed:
1. one per cent of the turnover in State or turnover in Union territory in case of a manufacturer;                                                                                                                                       2. two and a half per cent, of the turnover in State or turnover in Union territory in case of persons engaged in making supplies referred to in clause (b) of paragraph 6 of Schedule II; and
3. half per cent, of the turnover in State or turnover in Union territory in case of other suppliers.

(ICAI FAQ PUBLICATION 06-09-2017 COMPOSITION LEVY: FAQ NO. 53)

If all the Supplies of a person are under Reverse charge mechanism, can such person not register under the Act although the aggregate turnover is exceeding the prescribed limit

It is not necessary for the supplier to take registration since the Notification No. 05/2017- Central Tax dated June 19, 2017, provides for the same. For Example: – In case of an independent director providing services, and his only income is from independent directorship (or such other services covered under RCM) to the company, in this case the director won’t be required to take registration.

(ICAI FAQ PUBLICATION 06-09-2017 REVERSE CHARGE : FAQ NO. 52)