Notices:   The Assessment Office will assist the public by appointment only.  Please call 815-334-4290 to schedule an appointment.   The Administration Building lobby is open to accept any applications or other information that you would like to be reviewed by the office staff.

Due to Legislation, the Assessment Office will not require renewal applications for the 2020 Senior Assessment Freeze, Person with Disabilities,  or Disabled Veterans Exemption IF you submitted an approved 2019 application.  The Senior Assessment Freeze deadline has been extended to September 15, 2020.    

The 2019 Final Decision Notices were mailed on March 13, 2020. If you do not receive the notice by mail, you may obtain a copy going to the "Final Decision Notice" link on the left hand side of this screen..

 To view your current and past assessments for property in McHenry County please click here.

Mission Statement:

The Office of Assessments strives to administer an accurate, fair, uniform, and timely assessment of all real property in McHenry County in accordance with and as mandated by the Illinois Property Tax Code.

Function: It is the function of the county Office of Assessments to monitor and direct the countywide valuation of real property for the purpose of real estate taxation. This mandated function includes but is not limited to:

  • Provide assistance and information to the individual township assessors
  • Monitor all functions for compliance with state statutes and IL Department of Revenue procedures
  • Apply exemptions and preferential assessments
  • Analyze sales data and conduct sales ratio studies
  • Apply equalization factors
  • Provide proper taxpayer notification of assessments through mailed notices and publication
  • Monitor and direct an unbiased appeal procedure to assure due process
  • Prepare abstracts and reports for submission to the Illinois Department of Revenue
  • Timely certification of the completed assessment roll to the County Clerk in manner to facilitate timely tax calculation and billing as prescribed by statute
  • Assist Board of Review in defense of decisions when appealed to the Illinois Property Tax Appeal Board
  • Maintain Parcel Identification Numbering system
  • Maintain an accurate county cadastral map system, including line maps, and other property & owner information, to be used by the property tax function, other county offices, other governmental offices and the public, in conjunction with the county's Geographical Information System

Functional Divisions:

Assessments: Assists with and reviews the work of the township assessors and assures compliance with state statutes as to valuation of property; applies eligible preferential assessments; conducts sales ratio studies for application of equalization factors; implements and directs the notification process through publication and direct mail.

Board of Review: Is responsible for determination or recommendation of eligibility for certain exemptions; directs the appeal process, including hearing real estate assessment appeals, rendering decisions regarding value and defending decisions to the Illinois Property Tax Appeal Board.

Mapping: Using recorded and filed documents and in conjunction with other county offices, maintains and updates the county cadastral maps and parcel numbering system including legal description, tax code, ownership, mailing address and property location.