(a) In addition to amounts authorized to be subtracted from federal adjusted gross income pursuant to section twelve of this article, a modification reducing federal adjusted gross income is hereby authorized in the amount of any qualifying contribution to a qualified trust maintained for the benefit of a child with autism by the parent or guardian of a child with autism, up to a maximum of $1,000 per year for individual filers and persons who are married but filing separately, and $2,000 per year for persons who are married and filing jointly, but only to the extent the amount is not allowable as a deduction when arriving at the taxpayer's federal adjusted gross income for the taxable year in which the payment is made. This modification is available regardless of the type of return form filed. The taxpayer may elect to carry forward the modification over a period not to exceed four tax years, beginning in the tax year in which the payment was made: Provided, That the amount of the decreasing modification, in combination with all other decreasing modifications authorized pursuant to this article, shall in no event reduce taxable income below zero. Any unused decreasing modification carryforward amount remaining after the four-year carryforward period is forfeited. The accrued deposits and earnings on the qualified trust account for a child with autism and the subsequent withdrawal of funds from that trust account, made in accordance with the provisions of article sixteen, chapter forty-four of this code, shall not be treated as taxable income to either the trust or the beneficiary. The provisions of this section are effective for taxable years beginning on and after January 1, 2011.
(b) The following definitions apply to this section:
(1) "Autism" means "autism" as that term is defined in section one, article sixteen, chapter forty-four of this code.