(a) As used in this Code section, the term:

(1) "Accessibility features" means:

(A) One no-step entrance allowing access into the residence;

(B) Interior passage doors providing a 32 inch wide clear opening;

(C) Reinforcements in bathroom walls allowing later installation of grab bars around the toilet, tub, and shower, where such facilities are provided; and

(D) Light switches and outlets placed in accessible locations.

(2) "Taxpayer" means a permanently disabled person who has been issued a permanent permit under subsection (c) of Code Section 40-2-74.1 or a person who has been issued a special permanent permit under subsection (e) of Code Section 40-2-74.1.

(b) A taxpayer shall be allowed a credit against the tax imposed by Code Section 48-7-20 as follows:

(1) In the amount of $500.00 with respect to the purchase during that taxable year of a new, single-family home containing all of the accessibility features defined under subsection (a) of this Code section; or

(2) For qualifying expenditures made to retrofit an existing, single-family home with one or more accessibility features as defined under subsection (a) of this Code section, a credit shall be allowed with respect to each such accessibility feature in the amount of $125.00 or the actual cost of such accessibility feature, whichever is lower, provided that the aggregate amount of such credit under this paragraph for such accessibility features shall not exceed $500.00.

(c) In no event shall the total amount of the tax credit under this Code section for a taxable year exceed $500.00 per residence or the taxpayer's income tax liability, whichever is less. Any unused tax credit shall be allowed to be carried forward to apply to the taxpayer's next three succeeding years' tax liability. No such tax credit shall be allowed the taxpayer against prior years' tax liability.

(d) The commissioner shall promulgate any rules and regulations necessary to implement and administer this Code section.