Service Tax to GST

Santosh Sah (22 Points)

02 February 2018  
hi,
my client was taking advertising service from a company. There is a invoice of October 2016 which is booked in July 2017 is there any issue?. also, there was a payment outstanding of Rs. 500,000 to pay the advertising company by the client. but in the month of December 2017, the client has reversed one of the invoice but didn't reversed the service tax input took earlier at the time of booking that invoice. Now at the time of reversal it's need to reverse service tax or GST?