Interest payable on loans within a business year is deductible as expense or loss of that year.
Where the interest rate on loans as provided in the loan contracts exceeds the statutory rate, computation shall nevertheless be made according to the maximum interest rate chargeable by local commercial banks; provided that in case the collection authority-in-charge has determined the maximum interest rate with respect to a loan acquired from a source other than a bank by reference to the market rate, the maximum interest rate as determined by the collection authority-in-charge may apply.