Tax deduction at source on interest on securities must follow prescribed rates with specified exemptions and rounding rules. Directives require deduction of income tax at source from interest on Government securities at prescribed differentiated rates by payee category and security type, with defined treatment for residents, non residents, domestic and non domestic companies. Deductions are subject to valid exemption or abatement certificates; certain bonds, National Savings instruments and specified exempt recipients require no withholding subject to written declarations and statutory notifications. The circular defines domestic company for this purpose, mandates rounding of tax fractions to the nearest rupee, and advises consulting the Income tax Officer in doubtful cases.