Refund under GST: procedural eligibility, documentation and formulaic calculation govern zero rated and inverted credit claims. Refunds under GST arise from categories including zero rated supplies, SEZ supplies, exports under bond/LUT, deemed exports, inverted duty accumulations, excess electronic cash balances, excess tax payments and judicial orders. Provisional refunds are available only for zero rated claims and are processed separately for each tax head subject to statutory conditions; claims use prescribed forms and documentary validations, follow specific relevant date and limitation rules, and refunds of accumulated ITC or inverted rate credits are computed by statutory formulas using Net ITC and Adjusted Total Turnover.