Accumulation of income by registered non-profits allows prescribed set aside, investment, and Assessing Officer approval for purpose changes. Section 342 permits a registered non-profit organisation to accumulate part of its regular income for up to five years by furnishing a prescribed statement to the Assessing Officer specifying purpose and period; accumulated income must be invested in modes permitted under section 350 or applied for the stated purpose, transfers to other registered non-profits from accumulated funds are not treated as application, court-ordered delays exclude time from the five-year period, and the Assessing Officer may authorize change of purpose or permit transfer on dissolution.