Input tax credit apportionment: credits limited to business-use while specified supplies and personal uses are blocked. Section 17 restricts input tax credit to the portion attributable to business use or to taxable (including zero-rated) supplies where supplies are partly exempt; exempts specified items from credit (including reverse-charge supplies, securities, land and certain buildings). Banking and financial institutions may elect a monthly fifty per cent credit rule with conditions. Sub-section (5) enumerates blocked credits-motor vehicles (limited exceptions), specified services and goods, construction-related inputs for immovable property (other than plant and machinery), composition-scheme supplies, supplies to non-residents (except imports), personal consumption, lost/disposed goods, and taxes recovered under specified provisions. The Government may prescribe attribution methodology; 'plant and machinery' is defined with exclusions.