Functionality test for plant or machinery: specially designed buildings may qualify as plant for tax and input credit purposes. New machinery or plant includes items previously used abroad if not earlier used in India, imported, and not previously depreciated; the judicial distinction treats machinery as items that perform production functions and plant as items essential to enable production, but courts apply a functionality test so that a building specially planned and constructed to serve an assessee's technical requirements may be treated as plant for investment allowance and for CGST input exclusion purposes, with the ultimate determination being a question of fact.