It is important to note that assessment of property is just the beginning of the property tax process. The Assessor's Office has the responsibility to value property based on market value and equity. Once the Assessor's books are closed, those values are used by taxing bodies to actually formulate your tax bill.
The Assessor's work follows the assessment process each year and concludes with the closing of the books in the fall. Once the figures are factored by the Supervisor of Assessments and finalized by the Board of Review, the various taxing bodies begin the work of levying for their budgetary needs.
Each taxing body sets its levy against the total assessed valuations within its taxing district. The funds from the levy form the budget of the taxing body for the upcoming year. Taxing district lines often cross each other and overlap; your tax bill lists the taxing bodies that collectively provide services for your area of the Township. These taxing bodies include school districts, park districts, municipalities (for incorporated areas), county (for unincorporated areas), and many others. Though the tax cap limits the amount of levy increases from year to year, local referendums with appropriate notice, hearing, etc., can bypass this restriction. Additionally, new construction can be levied against at a different, higher rate than existing homes and businesses.
Once each taxing body determines its budget and sets its levy, they file for their tax extension with the County Clerk. The County Clerk must calculate each taxing body's levy against its total Equalized Assessed Valuation (EAV) to derive the tax rate. The individual tax rates for each taxing body that serves your area form your overall tax rate; you can see the elements of your tax rate listed on your tax bill.
Once tax rates are set, the Treasurer begins the collection process. In Will County, tax bills are mailed at the beginning of May and are paid in two installments. The first is due June 1st; the second is due September 1st.
The above represents a brief overview of the property tax process. The Assessor's work provides the valuation information that serves as the basis for the process, but the Assessor has no role in the setting of tax rates or the collection of tax payments.