Section 13(1)(d) of the Income-tax Act, 1961, deals with the forfeiture of tax exemptions for charitable or religious trusts and institutions if they invest in certain prohibited modes. This provision applies when a trust or institution, which otherwise qualifies for tax exemption under sections 11 and 12, invests its funds in ways that are not permitted under section 11(5). The significance of this section lies in ensuring that the funds of such trusts are invested in secure and approved avenues, thereby safeguarding the interests of the beneficiaries. The statutory test under this section involves verifying whether the trust has invested in any of the prohibited modes. The burden of proof lies on the trust to demonstrate compliance with the investment norms. In practice, this section is crucial for maintaining the integrity and financial prudence of charitable organizations.