GST applicable for the work

Dear Ganesh Bhat

As per Notification 2/2018 CT (r) .

Composite supply of goods and services in which the value of supply of goods constitutes not more than 25 per cent. of the value of the said composite supply provided to the Central Government, State Govt or UT local authority or a Government
Entity by way of any activity in relation to any function entrusted to a Panchayat under article 243 G of the Constitution or in relation to any
function entrusted to a Municipality under article 243W of the Constitution is EXEMPTED.

But as I think this service is cover under the work contract services define u/s 2(119) , though it's work contract it's taxable.

Now that's sure that it's Taxable Supply as consideration is received by supplier of Services provider & as per Section 9 of CGST Act the GST is leviable.

Such supply which is to be provided continuously or on recurrent basis under contract , for a period exceeding 3 months are cover under the Defination of continue supply of Services Define u/s 2(33) & as per Section 31(5) the invoice shall be issued (Get need to be discharge) on or before due date of payment, before or any time when supplier receives payment, on or before date of completion of work.
And in case of Services the GST need to be discharge on advance payment received.

So the question of estimate & actual expenditure (Actual cost) do not arise

So in this case, my father will have to pay applicable gst even though gst is not part of estimate and actual estimate is the expenditure of work ?