Place of supply for immovable property spanning states: allocate service supply to each state proportionately under contract or reasonable basis. The place of supply for services related to immovable property located in more than one State is treated as made in each State in proportion to the value of services attributable to that State as determined by the contract or, absent such contract, on a prescribed reasonable basis, per the Explanation to section 6(5) of the IGST Act.