Tax exemption for educational and medical institutions hinges on government financing, receipt thresholds and compliance conditions under section 10(23C). Exemption under section 10(23C) covers non profit educational institutions, philanthropic hospitals and approved charitable funds or trusts; entities wholly or substantially financed by government qualify where government grants exceed half of total receipts. Eligibility also depends on prescribed aggregate receipt ceilings for smaller institutions, application with audited accounts, exclusive application or limited accumulation of income, specified investment restrictions with listed exceptions, treatment of payments to other exempt entities, and authority to withdraw approval for non compliance.