Job work procedure: timelines for return or deemed supply and tax treatment on supplies from job workers. Section 143 permits a registered principal to send inputs or capital goods to a job worker without tax subject to prescribed conditions and time-bound return or supply obligations; the principal must keep proper accounts, and failure to return or supply within the applicable period results in the movement being deemed a supply by the principal. Waste and scrap may be supplied directly from the job worker's premises if the job worker is registered, otherwise the principal must supply and account for tax.