Taxability of construction services depends on treatment of consideration and timing of payment relative to completion certificate. Service tax on construction depends on characterization of consideration, timing of payment relative to completion certification, and parties in the contractual model. Builders' construction services are taxable where consideration (including land or development rights) is received before completion certificate; valuation for flats allotted to landowners is to mirror prices of similar flats sold to other buyers and tax is payable when possession or proprietary rights are transferred by conveyance or allotment. Special rules apply to redevelopment, investment, conversion, BOT and joint development models.