First of all, congratulations on buying a new flat. Secondly, as per the facts laid down by you, I wish to tell you that the rate of GST payable in this case depends on the location of the property. On the basis of the changes brought about in the GST regime applicable from 1st April 2019, the rate of GST on affordable housing would be 1% or 5% depending upon the size and location.
Affordable Housing as per the latest amendments to the Act includes any property having a carpet area i.e. the actual area of the fault, excluding any common or shared area of 60 square meter (645 sq. ft.) in the metropolitan cities like Delhi-NCR, Mumbai, Chennai, Kolkata, Hyderabad, Bengaluru and a property having a carpet area of 90 sq. m. (968 sq. ft.) in non-metropolitan cities.
So, if your flat is in one of the above-mentioned metropolitan cities, then you would have to pay 5% GST, as in this case your property would come under the category of a non-affordable housing project and if it is in any other city, then you need to pay 1% GST without Input Tax Credit (ITC) in both the cases.