Income taxes. Combining net worth. Tax return with state income tax return, §48-13-77. Insurance companies. Exemption of companies separately taxed, §48-13-71. Interest. Penalties, §48-13-79. Payment of tax, §48-13-77. Due date, §48-13-76. Effect, §48-13-78. Failure to pay timely, §48-13-79. Period for payment, §48-13-78. Penalties, §48-13-79. 327 INDEX CORPORATE NET WORTH TAX —Cont’d Returns, §48-13-77. Extension of time for filing, §48-13-79. Failure to file timely, §48-13-79. Table of amount of tax, §48-13-73. Taxable period less than six months. Amount of tax, §48-13-73. Time. Payment of tax, §48-13-77. Failure to pay timely, §48-13-79. Period for payment of tax, §48-13-78. Returns, §48-13-77.