65 ILCS 5/9-2-87
When the specified general officer in each county receives the report provided for, he shall proceed to obtain judgment against the lots and parcels of land and property for the special assessments and the special taxes, or installments thereof, and interest remaining due and unpaid, in the same manner as is or may be by law provided for obtaining judgment against lands for taxes due and unpaid the county or State except that in counties having a population of less than 1,000,000, no other notice of the application for this judgment shall be required than that specified in this Division 2 to be given by the collector of the municipality. The general collecting officer of the county shall proceed in the same manner to sell the same for the specified special assessments, special taxes, or installments thereof, and interest remaining due and unpaid except that in counties having a population of less than 1,000,000, no other notice of sale shall be required than that specified in this Division 2 to be given by the collector of the municipality. In obtaining these judgments and making this sale, the general collecting officer of the county shall be governed by the general revenue law of the State except as otherwise provided in this Division 2.
No application for judgment against land for unpaid special taxes or special assessments shall be made at a time different from the annual application for judgment against land upon which general taxes remain due and unpaid.
The application for judgment upon delinquent special assessments or special taxes in each year shall include only such special assessments, special taxes, or installments thereof, and interest, as have been returned as delinquent to the county collector on or before the first day of August in the year in which the application is made, and marked on the general tax books of the county collector on or before March 10, as provided in Section 9-2-81. However, in counties having a population of less than 1,000,000, such application shall include only the special assessments, special taxes, or installments thereof, and interest as have been returned or reported as delinquent to the general collecting officer of the county not less than 5 days prior to the date designated for application for judgment, in the year in which the application is made. Such judgment of sale shall include interest on matured installments up to the date of the judgment, as provided in this Division 2.
In the 5 years next following the completion of a general reassessment of real property in any county having a population of 1,000,000 or more, made pursuant to an order of the Department of Revenue of the State of Illinois, notwithstanding that those special assessments, special taxes, or installments thereof, and interest, have not been returned as delinquent to the county collector on or before the first day of August in the year in which the application is made, and notwithstanding that those special assessments, special taxes, or installments thereof, and interest, were not marked on the general tax books of the county collector on or before March 10 of the same year as provided in Section 9-2-81 or within 15 days after the county collector received the general tax books in that year, such an application shall be made on the first day of September for judgment and order of sale for special assessments, special taxes, or installments thereof, and interest, in each year on delinquent lands and lots. The county collector shall include in that application all special assessments, special taxes, and installments thereof, and interest, then remaining unpaid. Within 30 days after the county collector has received the general tax books the special assessments, special taxes, or installments thereof, and interest, then remaining unpaid, shall be marked therein, and if for any reason, that application cannot be made on the first day of September, it shall be made at any time not later than the first day of the next succeeding January.
In counties having a population of less than 1,000,000, the application for judgment and order of sale, and the sale, shall be made on the respective days previously designated by the general collecting officer of the county.
65 ILCS 5/9-2-87