Although the designated member is responsible for filing the return and remitting payments, any CIT liability belongs to the "taxpayer," i.e., the unitary business group, and not merely to the designated member. Accordingly, if the group's CIT liability is not paid, the Department may look to each member of the unitary business group that has nexus with Michigan to collect the tax that is due, as well as any penalties and interest that may be assessed. In other words, each member of a unitary business group is jointly and severally liable for any CIT assessment, and the Department may pursue any or all such members to satisfy the entirety of the assessment. Joint and several liability means that all members of the unitary business group with nexus with Michigan are collectively and individually liable for the full amount of the group's tax liability.