Trust exemption limits: denial of tax exemption when trust income or assets benefit founders or related persons. Section 13 narrows application of the exemption under section 11 where trusts or institutions confer private or particular benefits: it denies exemption for income of private religious property, for trusts created for a particular religious community or caste, and where trust income or property inures to certain persons. The provision lists specific deeming events (e.g., inadequate security or remuneration, rent, overpayment or underpayment in transactions, diversion of income, and investments in concerns with substantial interest by such persons) and defines the relevant persons (founder, substantial contributors, relatives, family members, and related concerns). A limited investment proportion exception and explanatory definitions are provided.