A. Corporations that are part of a unitary group shall file a return properly reporting and paying tax on taxable income as a worldwide combined group unless they properly elect to report and pay tax on taxable income as a water’s-edge or consolidated group, pursuant to department rules and instructions, on the first original return required to be filed for taxable years beginning on or after January 1, 2020. Corporations electing to file a consolidated return must file on that same basis for federal income tax purposes. Once a unitary or consolidated group has properly made an election to file as a water’s- edge or consolidated group, the group and any of the group’s members shall file a return on that basis for at least seven consecutive years unless the secretary grants permission otherwise. Corporations that are part of a unitary group filing a return are jointly and severally liable for the tax imposed pursuant to the Corporate Income and Franchise Tax Act on taxable income.

B. Corporations required to file a return as part of a filing group pursuant to this section may designate a member of the group to act as the principal corporation to file the return, make any elections, claim tax credits or refunds or perform any other act on behalf of the group with respect to the corporate income tax; provided that the members of the group remain jointly and severally liable for the taxes due pursuant to Subsection A of this section.