Central Government exemption power allows notification-based exemption of classes of companies from section 104 subject to conditions. The amendment grants the Central Government power to exempt classes of companies from section 104 by notification subject to conditions, adds a related cross-reference, and excludes from the section Indian companies principally engaged in manufacture, processing, mining or generation/distribution of power and Indian companies whose machinery or plant capital value meets a specified threshold; an explanation treats the activities as mainly carried on where income from them forms a majority of the company's total income for the relevant year.