Interest liability for tax withholding: escalating monthly interest applies for delayed deduction and further increased interest until payment. Amendment imposes a statutory interest liability on persons, principal officers or companies who fail to deduct or to pay deducted tax: simple interest is payable from the date the tax was deductible until the date it is deducted, and at a higher rate from the date it is deducted until actual payment; such interest must be paid before furnishing the withholding statement.