Duty exemption schemes permit duty free import or remission of inputs for export production, with value addition and user conditions. Chapter 4 establishes duty exemption and remission mechanisms: Advance Authorisation and DFIA for duty free import of inputs (with actual user, transferability and value addition requirements), and DEPB and drawback for post export duty neutralisation; it specifies admissible inputs, exemptions from basic and additional customs duties unless excluded, SION based issuance, CENVAT implications, transfer and endorsement rules, and a specialised Gems and Jewellery regime with replenishment authorisations, valuation and wastage norms.