In terms of Section 5 of the Income Tax Act, every natural person, who receives taxable income, is obliged to pay income tax on that income. In terms of Section 66 of the same Act, every person, who is liable to tax, must submit a tax return, as prescribed by the Commissioner. The Act doesn’t prescribe exemptions for the submission of a tax return.
If you’re a registered taxpayer, you must submit a return for every year of assessment. The Commissioner’s notice is clear: If you receive interest income, you must submit a tax return. This obligation remains, even if a portion of that interest income is exempt from tax.