Supervisor of Assessments

The Supervisor of Assessments Office identifies and places a value on approximately 52,000 parcels.


Supervisor of Assessments

Alex Simpson, C.I.A.O.

Flood Plain Coordinator / Plat Officer for Williamson County / Supervisor of Assessments

Williamson County Administration Building
407 N. Monroe Street, Suite 205
Marion, IL 62959

Phone: 618-998-2189
Phone: 618-997-1301 Ext. 1181


Last day to file 2023 Board of Review Complaint will be May 20, 2024.

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Learn About Exemptions Learn How Farmland Is Assessed View Assessment Change Publication Learn About The Board of Review Request to Intervene Form View Williamson Co. Flood Plain Ordinance View Williamson Co. Subdivision Ordinance Research Property Assessments Read IL Property Tax Code Apply for a Building Permit Review Building Permit Ordinance View Green Energy Ordinance