Registration timing for trusts: prescribed applications and specified advance notices now govern tax registration eligibility and deadlines. Insertion of clause (ac) in section 12A requires the person in receipt of income to apply in the prescribed form and manner to the Principal Commissioner or Commissioner for registration under section 12AB according to specified timelines (transitional, renewal, provisional registration, modification of objects, or prior year filing) and links the applicability of sections 11 and 12 to the sub clause under which such application is made; related substitutions adjust the filing trigger to the specified date in audit provisions and expand proviso references to include section 12AB.