work contract bill

Prima facie, you are suppossed to charge GST over the tax bill issued to Government.

The service receiver here is not under RCM to deduct and pay any GST amount.

At most, they would have deducted 1% TDS ( though not applicable as on date) over the bill, subject to proviso of the section.

So, please check the exact nature of deduction and take call.

Also check whether the bill issued was for the period ending June 2017, i.e. of the earlier ST/VAT  regime.....

@ Raja: Yes, your assumption is also correct.......... but here queriest has mentioned 'deducted GST'

So, let him check & verify first.