Section 220.709 - Deficiency determinations(1) As soon as practicable after a return is filed, the department shall examine it to determine the correct amount of tax. If the department finds that the amount of tax shown on the return is less than the correct amount and the difference is not solely the result of mathematical error, it shall issue a notice of deficiency to the taxpayer, setting forth the amount of additional tax and any penalties proposed to be assessed. The findings of the department under this subsection shall be prima facie correct and shall be prima facie evidence of the correctness of the amount of tax and penalties due.(2) If a taxpayer fails to file a tax return, the department shall determine the amount of tax due according to its best judgment and information, and it shall issue a notice of deficiency to the taxpayer, setting forth the amount of tax and any penalties proposed to be assessed. The amount so determined by the department shall be prima facie correct and shall be prima facie evidence of the correctness of the amount of tax due.(3) An erroneous refund shall be considered deficiency of tax on the date made, and shall be deemed assessed and shall be collected as provided in ss. 220.703 and 220.707.s. 19, ch. 71-359; s. 47, ch. 91-112.