35 ILCS 200/21-25
2021 Illinois Compiled Statutes|Chapter 35 - REVENUE|35 ILCS 200/ - Property Tax Code.|Title 7 - Tax Collection

Sec. 21-25. Due dates; accelerated billing in counties of 3,000,000 or more.   Except as hereinafter provided and as provided in Section 21-40, in  counties with 3,000,000 or more inhabitants  in which the accelerated method of billing and paying taxes provided for in  Section 21-30 is in effect, the estimated first installment of unpaid taxes  shall be deemed delinquent and shall bear interest after March 1 at the rate of  1 1/2% per month or portion thereof until paid or forfeited. For tax year 2010, the estimated first installment of unpaid taxes shall be deemed delinquent and shall bear interest after April 1 at the rate of 1.5% per month or portion thereof until paid or forfeited.  For all tax years, the second  installment of unpaid taxes shall be deemed delinquent and shall bear interest  after August 1 annually at the same interest rate until paid or forfeited.  Notwithstanding any other provision of law, if a taxpayer owes an arrearage of taxes due to an administrative error, and if the county collector sends a separate bill for that arrearage as provided in Section 14-41, then any part of the arrearage of taxes that remains unpaid on the day after the due date specified on that tax bill  shall be deemed delinquent and shall bear interest after that date at the rate of  1 1/2% per month or portion thereof.If the county board elects by ordinance adopted prior to July 1 of a levy  year to provide for taxes to be paid in 4 installments, each installment for  that levy year and each subsequent year shall be deemed delinquent and shall  begin to bear interest 30 days after the date specified by the ordinance for  mailing bills, at the rate of 1 1/2% per month or portion thereof, until paid  or forfeited.Payment received by mail and postmarked on or before the required due date  is not delinquent.Taxes levied on homestead property in which a member of the National Guard or  reserves of the armed forces of the United States who was called to active duty  on or after August 1, 1990, and who has an ownership interest, shall not be  deemed delinquent and no interest shall accrue or be charged as a penalty on  such taxes due and payable in 1991 or 1992 until one year after that member  returns to civilian status.If an Illinois resident who is a member of the Illinois National Guard  or a reserve component of the armed forces of the United States  and who has an ownership interest in property taxed under this Act is  called to  active duty  for deployment outside the continental United States  and  is on active duty on the due date of any installment of taxes due under  this Act, he or she shall not be deemed delinquent in the payment of the  installment and no interest shall accrue or be charged as a penalty on the  installment until 180 days after that member returns to  civilian  status.  To be deemed not delinquent in the payment of an installment of taxes and any  interest  on that installment, the reservist or guardsperson must make a reasonable effort to notify the county clerk and the county collector of his or her activation to active duty and must notify the county clerk and the county collector  within 180  days after his or her deactivation and provide verification of the date of his  or her  deactivation. An installment of property taxes on the property of any reservist  or  guardsperson who fails to provide timely notice and verification of  deactivation to the  county clerk is subject to interest and penalties as delinquent taxes under  this Code from  the date of deactivation.    (Source: P.A. 98-286, eff. 1-1-14.)