Charitable trust registration determines income-tax exemption; timing, audit and return compliance govern entitlement to relief. Exemption under sections 11 and 12 requires registration in the prescribed form and timely compliance; delayed applications attract application-year or earlier effective dates depending on tax-authority satisfaction. Registration under the reformed regime governs validity and time-limits. Trusts exceeding prescribed income thresholds must maintain books, obtain a chartered accountant audit and furnish the prescribed audit report form, with specific forms required where foreign contribution, application outside India or high income conditions arise. Return filing in the prescribed trust return form within statutory time-limits is mandatory.