Time of supply - Residual cases

In which act you want to know

income tax or fema?

CGST Act

Both are deals with same condition, difference is only one is for goods , another is for servcies

let me explain the same by eg.

If the date of Invoice of the Supplier of Services is 01.01.2018 and the Date of payment, received by the Supplier is 06.03.2018, the earlier being the Date of Invoice, 01.01.2018, is the Time of Supply. Liability of payment of Tax has arisen and therefore Tax is payable under Forward charge on the date of filing of Monthly or Quarterly return, for the month of January, 2018.

yes. thank you Pankaj Rawat.
can you please tell me in which circumstances we will use section 12(5) and 13(5) of CGST ACT?