Job work under GST triggers principal's responsibility for goods and deemed supply consequences if return timelines lapse. A registered principal may send inputs or capital goods to a job worker without payment of tax under prescribed conditions; inputs must be returned within one year and capital goods within three years or be deemed supplied by the principal to the job worker on the date of dispatch. The principal bears responsibility for maintaining accounts and documentation and must declare the job worker's premises as an additional place of business before supplying from there, subject to limited exceptions. Waste and scrap may be supplied by a registered job worker on payment of tax or by the principal if the job worker is unregistered.