Permission for job work by export units requires application, sample retention, identity verification, and bank guarantees to protect duty interests. EOUs and EPZ/STP/EHTP/SEZ units require application to the jurisdictional Assistant/Deputy Commissioner with details of the job-worker, processing activities, and justification; permission for job-work may be granted normally for one year and shall not be refused solely because the job-worker lacks Central Excise registration. Safeguards include sample retention and identity verification on return, bank guarantees to cover duty forgone for raw removals and partial guarantees for semi-processed removals with exemptions for status holders of good record, mandatory return within thirty days subject to limited extensions, and expeditious verification of job-worker premises by authorities.