GST rate change for construction services: differentiated state tax rates, ITC transition rules, and promoter option to elect alternate rate. Amendments restructure state tax rates for construction services, distinguishing affordable residential, other residential, commercial and composite works, permit a one time option for promoters of ongoing projects to elect an alternate rate, require payment of specified state tax from the electronic cash ledger, and tightly regulate input tax credit use through project wise computation and Annexure formulas. The changes impose reverse charge for supplies from unregistered persons (including a specific entry for services supplied by unregistered persons to promoters), mandate project wise records, end of year shortfall calculations and prescribed reporting, and add detailed definitions and procedural forms for compliance under the transitional regime.