Gst or service tax for uc flat booked before 1st july 17

First of all, you need to check your property purchase agreement with respect to the consideration clause as to whether the consideration demanded by the property developer is written as "Base amount + Applicable Taxes" or there might be a separate clause in your agreement stating that any alterations due to changes in taxes made applicable by the Govt shall be borne by the customer. If yes, then you will need to pay the balance 10% amount with GST.

 Otherwise, you can pay the balance agreed upon amount (with ST component) to the property developer and negotiate with him accordingly.

thanks.