Nil tax declaration prevents tax deduction at source when furnished, subject to income ceiling and prescribed procedure. No tax is to be deducted at source where an eligible payee furnishes a prescribed, verified duplicate declaration that tax on his estimated total income for the relevant year will be nil; the payer must send one copy to the tax commissioner within seven days. The exemption is subject to disqualification if the income or aggregate payments exceed the basic non-taxable amount. Special provisions allow senior citizens, certain non-company/non-firm persons, Offshore Banking Unit transactions with non-residents, payments to the New Pension System Trust, and government-notified classes to claim no or lower deduction under specified withholding heads.