Contractors. Classified subcontractors. Deduction for payments to, §48-7-38. Cooperative hospital service organizations. Exempt organizations, §48-7-25. Corporate net worth tax. Combining net worth. Tax return with state income tax return, §48-13-77. Corporations, §48-7-21. Allocation of income. Application for permission to use other method, §48-7-35. Applicability of tax imposed to entire net income, §48-7-31. Apportionment of income, §48-7-31. Agreement establishing allocation and apportionment. Conditions for, §48-7-31.1. Three factor formula, §48-7-31. Assignment of credits, §48-7-42. Combining net worth tax return with state income tax return, §48-13-77. Credit card data processing and related services. Apportionment of income, §48-7-31. Deductions for payments to classified subcontractors, §48-7-38. Dissolved corporations. Action for collection of tax out of assets, §48-7-83. Distorting taxable income, §48-7-58. Electronic filing for nonindividual taxpayers, §48-7-54. Estimated income tax, §48-7-117. Credits, §48-7-121. Defined, §48-7-117. 418 INDEX INCOME TAXES —Cont’d Corporations —Cont’d Estimated income tax —Cont’d Failure to pay, §§48-7-120, 48-7-126. Willful failure to pay, §48-7-127. Installment payments, §48-7-119. Interest on refunds, §48-7-121. Overpayments. Credit or refund, §48-7-121. Underpayment, §48-7-120. Exempt corporations and organizations, §48-7-25. Gross receipts factor. Apportionment of income, §48-7-31. Investment income. Not subject to apportionment, §48-7-31. Payroll factor.