Refund procedure: prescribed claims with documentary proof; provisional advances permitted for zero-rated supplies pending verification. Refunds of tax, interest or other amounts must be claimed in prescribed form within statutory time limits from the relevant date; registered persons may claim unutilised input tax credit refunds only in specified situations such as zero-rated supplies. Applications require prescribed documentary evidence, though small claims may be certified by declaration. The proper officer may grant provisional refunds for zero-rated supplies subject to verification, issue final orders within the statutory period, and withhold or deduct refunds where returns or liabilities remain outstanding or where revenue risk from proceedings or malfeasance is indicated.