(1) The commission shall make the inquiries, determinations, and assessments of all taxes (including interest, additional amounts, additions to the tax, and assessable penalties) imposed by this chapter or former chapters imposing income taxes.
(2) The assessment shall be made by recording the liability of the taxpayer in the office of the commission in accordance with rules prescribed by the commission. The commission may, at any time within the period prescribed for assessment, make a supplemental assessment if it is ascertained that any assessment is imperfect or incomplete in any material respect.