The Illinois Appellate Court has agreed with the Department of Revenue and the Circuit Court by upholding a prior decision to subject eligible delinquent taxpayers who did not pay all outstanding taxes during the amnesty period to penalties and interest at twice the statutory rate. A taxpayer subject to the double penalties and interest challenged the Amnesty Act by alleging that it violated the Illinois Statute on Statutes and the Uniformity clauses of the Illinois Constitution. The Appellate Court determined that the Act did not violate the Uniformity Clause because it drew a real and substantial difference between those who paid their liabilities during the amnesty period and, as a result received a waiver of penalties and interest, and those who did not and, thus, were subject to double penalties and interest. Further, the Court found that the Statute on Statutes was not violated because the imposition of double penalties and interest was not truly retroactive but, rather, applied prospective by reason of neglecting to take advantage of the amnesty window. (Advanced On-Site Concrete, Inc. v. Illinois Department of Revenue, No. 1-06-3426, May 22, 2008)