Service tax on pure residential flat 11 no.

Dear all,

There are many posts reflecting many beleifs regarding service tax on upcoming flat type of building construction.

Ended up with confusion only.

Now,

1. If somebody planned and about to execute a Purely Residential Apartment type building, (with 11 number flats, may be possible to get increased to even 13 flats - if permission for more flats got).
2. If the part payment of total consideration is to be taken step by step in due course of construction,

How and at what rate the service tax should be levied and at what time it should be paid?