Article 371(F) of the Indian Constitution and Section 10(26AAA) of the Income Tax Act, 1961, ensure Sikkim's income tax exemption. This applies to all income, including interest on securities and dividends, for individuals recognized as Sikkimese under the Sikkim Subjects Regulation Act, 1961. In contrast, other Indian residents must file income tax returns by July 31 if their income exceeds the specified limit.