How to ascertain the time of supply of services

In terms of Section 13 of the CGST Act, 2017 read with Section 31(2) thereof and Rule 47 of the CGST Rules, 2017, if the invoice is issued before supply of service or within a period of thirty days from the date of supply of service, the time of supply of services shall be the earliest of the following:
(a) Date of issue of invoice; or
(b) Date when the payment entry in relation to supply of services is recorded in
books of accounts of the supplier; or
(c) Date on which the payment is credited to supplier’s bank account.                      Illustration:

Date of invoice August 31, 2017 Time of supply of services shall be August 10, 2017
Date of supply of service August 7, 2017
Payment received by way of cheque and the entry for receipt of payment is recorded in books of accounts August 10, 2017
Amount credited to bank account of supplier August 12, 2017

However, if the invoice is not issued within a period of thirty days from the date of supply of service, in terms of aforesaid provisions i.e., Section 13 of the CGST Act, 2017 read with Section 31(2) thereof and Rule 47 of the CGST Rules, 2017, the time of supply of service shall be the earliest of the following:
(a) Date of provision of service; or
(b) Date when the payment entry in relation to supply of services is recorded in
books of accounts of the supplier; or
(c) Date on which the payment is credited to supplier’s bank account.                      Illustration:

Date of invoice August 31, 2017 Time of supply of services shall be July 7, 2017
Date of supply of service July 7, 2017
Payment received by way of cheque and the entry for receipt of payment is recorded in books of accounts August 10, 2017
Amount credited to bank account of supplier August 12, 2017

In a case where neither of the aforesaid provisions apply, the date on which the recipient shows the receipt of services in his books of account shall be the time of  supply of the services.

(ICAI FAQ PUBLICATIONS 06-09-2017  TIME OF SUPPLY OF SERVICES: FAQ NO. 14)