Deduction for agricultural extension project expenditure allowed, subject to notification and exclusive claim restriction provision. A deduction is available for expenditure on Board-notified agricultural extension projects undertaken in accordance with prescribed guidelines, originally allowing an enhanced one-and-one-half-times allowance but amended to operate on a single-times basis for later assessment years; such expenditure, once claimed and allowed, cannot be deducted under any other provision of the Income-tax Act for the same or any other assessment year.