Strict compliance with exemption conditions: declaration and filing deadline mandatory; revised returns cannot introduce new exemption claims.

The Court held that both conditions for claiming the exemption-furnishing a written declaration to the assessing officer and submitting it before the due date for the original return-are mandatory and must be strictly complied with. It rejected treating the time limit as directory, distinguished deduction-related authorities, and held that a revised return cannot introduce new exemption claims or claim carry-forward benefits not made in the original return.

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