(35 ILCS 200/9-260)
    Sec. 9-260. Assessment of omitted property; counties of 3,000,000 or more.
    (a) After signing the affidavit, the county assessor shall have power, when directed by the board of appeals (until the first Monday in December 1998 and the board of review beginning the first Monday in December 1998 and thereafter), or on his or her own initiative, subject to the limitations of Sections 9-265 and 9-270, to assess properties which may have been omitted from assessments for the current year and not more than 3 years prior to the current year for which the property was liable to be taxed, and for which the tax has not been paid, but only on notice and an opportunity to be heard in the manner and form required by law, and shall enter the assessments upon the assessment books. Any notice shall include (i) a request that a person receiving the notice who is not the current taxpayer contact the office of the county assessor and explain that the person is not the current taxpayer, which contact may be made on the telephone, in writing, or in person upon receipt of the notice, and (ii) the name, address, and telephone number of the appropriate personnel in the office of the county assessor to whom the response should be made. Any time period for the review of an omitted assessment included in the notice shall be consistent with the time period established by the assessor in accordance with subsection (a) of Section 12-55. No charge for tax of previous years shall be made against any property if (1) the assessor failed to notify the board of review of the omitted assessment in accordance with subsection (a-1) of this Section; (2) the property was last assessed as unimproved, the owner of such property gave notice of subsequent improvements and requested a reassessment as required by Section 9-180, and reassessment of the property was not made within the 16 month period immediately following the receipt of that notice; (3) the owner of the property gave notice as required by Section 9-265; (4) the assessor received a building permit for the property evidencing that new construction had occurred or was occurring on the property but failed to list the improvement on the tax rolls; (5) the assessor received a plat map, plat of survey, ALTA survey, mortgage survey, or other similar document containing the omitted property but failed to list the improvement on the tax rolls; (6) the assessor received a real estate transfer declaration indicating a sale from an exempt property owner to a non-exempt property owner but failed to list the property on the tax rolls; or (7) the property was the subject of an assessment appeal before the assessor or the board of review that had included the intended omitted property as part of the assessment appeal and provided evidence of its market value.
    (a-1) After providing notice and an opportunity to be heard as required by subsection (a) of this Section, the assessor shall render a decision on the omitted assessment, whether or not the omitted assessment was contested, and shall mail a notice of the decision to the taxpayer of record or to the party that contested the omitted assessment. The notice of decision shall contain a statement that the decision may be appealed to the board of review. The decision and all evidence used in the decision shall be transmitted by the assessor to the board of review on or before the dates specified in accordance with Section 16-110.
    (b) Any taxes based on the omitted assessment of a property pursuant to Sections 9-260 through 9-270 and Sections 16-135 and 16-140 shall be prepared and mailed at the same time as the estimated first installment property tax bill for the preceding year (as described in Section 21-30) is prepared and mailed. The omitted assessment tax bill is not due until the date on which the second installment property tax bill for the preceding year becomes due. The omitted assessment tax bill shall be deemed delinquent and shall bear interest beginning on the day after the due date of the second installment (as described in Section 21-25). Any taxes for omitted assessments deemed delinquent after the due date of the second installment tax bill shall bear interest at the rate of 1.5% per month or portion thereof until paid or forfeited (as described in Section 21-25).
    (c) The assessor shall have no power to change the assessment or alter the assessment books in any other manner or for any other purpose so as to change or affect the taxes in that year, except as ordered by the board of appeals (until the first Monday in December 1998 and the board of review beginning the first Monday in December 1998 and thereafter). The county assessor shall make all changes and corrections ordered by the board of appeals (until the first Monday in December 1998 and the board of review beginning the first Monday in December 1998 and thereafter). The county assessor may for the purpose of revision by the board of appeals (until the first Monday in December 1998 and the board of review beginning the first Monday in December 1998 and thereafter) certify the assessment books for any town or taxing district after or when such books are completed.
(Source: P.A. 96-1553, eff. 3-10-11.)