rate of gst deduction by govt on civil work contractor

If someone quoted govt work contract tender before the implementation of gst and his payment is reflecting in bank account after gst implementation (after 2-3 months ) Does he have to pay gst on work contract ??
Eg. If contract of Road of amount 23 lacs quoted on 28 june and payment will received after 2-3 months later from quoted date.How much gst will have to pay ?

GST is not apply in some condition:- 1. work is completed before 1 july,. 2. Bill is submitted before 1 july. Otherwise gst will payable.

abrar if he is registered then u need not to pay. he will charge from u in his bill

If a contractor submitt bill May-2017 does not pay his bill in the office before the June for any reason, and makes payment in July, then what would be the deduction of GST or VAT?

Railway civil contract work if any applicable cess