What are the different types of supplies which are liable to tax under reverse charge mechanism

As per Section 9 of the CGST Act, 2017 there are two types of supplies which are liable to tax under reverse charge mechanism: –
1. As per sub-section 3 specified categories of supply of goods or services or both as notified by Government on recommendations of the Council.
2. As per sub-section 4 Supply of taxable goods or services or both by an unregistered supplier to a registered person.                                                                          However, the supplies made by unregistered suppliers to a registered person are exempted, if the aggregate value of such supplies does not exceed 5,000/- in a day.

(ICAI FAQ PUBLICATION 06-09-2017 LEVY AND COLLECTION:  FAQ NO. 18)