(1) The amount of tax which is shown to be due on any return shall be deemed assessed on the date of filing the return, including any amended returns showing an increase of tax. In the event the amount of tax is understated on the taxpayer’s return due to a mathematical error, the department shall notify the taxpayer that the amount of tax in excess of that shown on the return is due and has been assessed. Such notice of additional tax due shall not be considered a notice of deficiency, nor shall the taxpayer have any right of protest. In the case of a return properly filed without a computation of the tax due, the tax computed by the department on the basis of the return shall be deemed assessed on the date the return is filed.
(2) Whenever a notice of deficiency has been issued, the amount of the deficiency shall be deemed assessed on the date provided in s. 220.713 if no protest is filed or, if a protest is filed, on the date when the decision of the department with respect to the protest becomes final.
(3) Any amount paid as tax or in respect to tax under this chapter shall be deemed assessed upon the date of receipt of payment.