Unjust enrichment rule directs refunds to Consumer Welfare Fund unless prescribed exceptions allow direct payment to claimant. Refund applications must include documentary evidence (assessment documents, sales invoices, etc.) proving excess payment and non-passing on of incidence; complete applications receive prescribed acknowledgements while incomplete ones are returned for correction. Customs examines complete claims to determine refundable amounts and issues refund orders where due. As a rule against unjust enrichment, refundable amounts are to be transferred to the Consumer Welfare Fund, except where specified exceptions permit direct payment to the applicant, including non-passing on of incidence, personal use imports, export duty refunds, drawback refunds, notified applicant classes, and evident excess payment in self-assessed or reassessed bills of entry.