Income tax; disallowance of itemized deductions; calculation

(1) Any taxpayer whose federal adjusted gross income is larger than the threshold amount determined under section 68 of the Internal Revenue Code of 1986, as amended, for the disallowance of itemized deductions shall calculate the amount of the excess.

(2) A taxpayer's tax liability shall be increased by an amount determined under this subsection. The amount shall be calculated by multiplying the maximum individual tax rate by ten percent of the excess calculated in subsection (1) of this section and subtracting the amount of the tax from the tax tables on ten percent of the excess from the result. The difference shall be the increase in the tax liability. If taxable income is less than ten percent of the excess, the calculation in this subsection shall be made using taxable income.