Investment allowance for new plant and machinery under section 32AC is limited to specified companies and locked in for five years. Section 32AC provides an investment allowance to encourage substantial investment in new plant and machinery by companies engaged in manufacture or production. The allowance is available only for specified acquisitions and installations under the 100-crore and 25-crore schemes, at 15% of actual cost subject to the stated conditions. A five-year lock-in period applies, and transfer within that period generally triggers treatment of the deduction as business income, subject to amalgamation or demerger exceptions.