1. As used in this section, the following terms mean: (1) “Benefits”, any Social Security benefits received by a taxpayer age sixty-two years of age and older, or Social Security disability benefits; (2) “Taxpayer”, any resident individual.

2. For the taxable year beginning on or after January 1, 2007, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to twenty percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. For the taxable year beginning on or after January 1, 2008, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to thirty-five percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. For the taxable year beginning on or after January 1, 2009, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to fifty percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. For the taxable year beginning on or after January 1, 2010, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to sixty-five percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. For the taxable year beginning on or after January 1, 2011, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to eighty percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. For all taxable years beginning on or after January 1, 2012, any taxpayer shall be allowed to subtract from the taxpayer’s Missouri adjusted gross income to determine Missouri taxable income a maximum of an amount equal to one hundred percent of the amount of any benefits received by the taxpayer and that are included in federal adjusted gross income under Section 86 of the Internal Revenue Code of 1986, as amended. A taxpayer shall be entitled to the maximum exemption provided by this subsection:

(1) If the taxpayer’s filing status is married filing combined, and their combined Missouri adjusted gross income is equal to or less than one hundred thousand dollars; or

(2) If the taxpayer’s filing status is single, head of household, qualifying widow(er), or married filing separately, and the taxpayer’s Missouri adjusted gross income is equal to or less than eighty-five thousand dollars.

3. If a taxpayer’s adjusted gross income exceeds the adjusted gross income ceiling for such taxpayer’s filing status, as provided in subdivisions (1) and (2) of subsection 2 of this section, such taxpayer shall be entitled to an exemption equal to the greater of zero or the maximum exemption provided in subsection 2 of this section reduced by one dollar for every dollar such taxpayer’s income exceeds the ceiling for his or her filing status.

4. The director of the department of revenue may promulgate rules to implement the provisions of this section. Any rule or portion of a rule, as that term is defined in section 536.010, that is created under the authority delegated in this section shall become effective only if it complies with and is subject to all of the provisions of chapter 536 and, if applicable, section 536.028. This section and chapter 536 are nonseverable and if any of the powers vested with the general assembly pursuant to chapter 536 to review, to delay the effective date, or to disapprove and annul a rule are subsequently held unconstitutional, then the grant of rulemaking authority and any rule proposed or adopted after August 28, 2007, shall be invalid and void.