The Geographic Information Systems (GIS) staff is mandated by Idaho Code to map over 1,000 different taxing districts comprised of more than 3,000 tax code areas (TCA), to ensure that all areas are in compliance with Idaho Statutes and the Idaho State Tax Commission’s (ISTC) Administrative Rules (IDAPA), and that property taxes are administered fairly and equitably.
All Idaho property lays within a combination of taxing districts. When taxing district jurisdictional boundaries overlap, they form a unique entity know as a Tax Code Area (TCA). Taxing districts submit boundary changes to ISTC throughout the year, and the GIS team maps these changes for the upcoming year.
District boundary changes and annexations submitted to ISTC will take effect during the next calendar year. For example, requests submitted to ISTC during 2026 will take effect in 2027.
Annexation Submissions
Annexation Process
Taxing Districts
Entities with authority
to levy a property tax
Data and Maps
Downloadable data and maps
Tax Code Areas
Unique entities known
as a Tax Code Area (TCA)
Historical Documents
View ordinances and other documentation
Proposed Annexations
Proposed changes to the counties
Mapping Support
Learn with our GIS resources
Contact Us
Contact our GIS department