The first tax records of Illinois were created in the late 1700s to early 1800s while Illinois was part of the Northwest Territory. These recorded an assessment for property tax on unimproved land. If payment became delinquent, the property was sold at public auction. However, most tax records created before statehood in 1818 have been lost.
After Illinois became a state, tax records of various kinds were kept in the counties, where records began about 1817. Examples of the kind of tax records you might find are: land taxes, poor taxes, school taxes, and county road taxes. A person was also taxed for having bank stock, slaves, and indentured Blacks or Mulattoes.
While tax lists are often used as substitutes for missing census records, in Illinois they do not represent every household. Those who did not own taxable land or property were not listed. No voting or poll taxes were imposed. Most Illinois land purchased from the federal government was not taxable for five years. Therefore, a person appearing on a tax list for the first time may have actually lived in the area for several years.
Many tax records are housed in the county seats of each county. They include assessors’ books, railroad tax books, collectors’ books, taxable land lists, delinquent taxes, and road tax books. Some original and microfilmed copies are in the Illinois Regional Archives Depositories (IRAD). See the IRAD wiki page for an explanation of IRAD and its holdings.
The Family History Library has microfilm copies of some Illinois tax records. A list of persons taxed during the Civil War is:
United States. Bureau of Internal Revenue. Internal Revenue Assessment Lists for Illinois, 1862–1866. National Archives Microfilm Publications, M0764. Washington, D.C.: National Archives, 1968?. (Family History Library film 1534562–624.) This extensive tax list shows monthly and annual taxes on personal property, income, those who produced and distributed goods, and on licenses to practice and do business. Illinois was divided into 13 tax districts. Cook County is in District 1, Sangamon County in District 8, Peoria County in District 5, and St. Clair County in District 12. Each film has a full list of counties and the districts to which they belonged.
Illinois taxation records can be found in the Family History Library Catalog by using a Place Search under:
ILLINOIS, [COUNTY]- TAXATION
ILLINOIS, [COUNTY], [TOWN]- TAXATION