Idaho annexations are governed by Statute 50-222 and Administrative Code (IDAPA) 35.01.03. Idaho State Tax Commission (ISTC) cannot advise on legal matters, so any questions about Idaho law should be brought to your legal team.
All documentation needs to be signed by December 31 and filed with ISTC within 30 days of signature and by January 10 to be included in the next effective year. For instance, a document signed on December 26, 2025, and received by ISTC on January 3, 2026, will be incorporated into 2026 tax year. A documented signed on December 26, 2025, and received by ISTC on January 25, 2026, will be incorporated into the 2027 tax year.
How to Submit an Annexation
An ordinance, order, or resolution must (see IDAPA 35.01.03.225):
- Be signed by the appropriate district officials
- Provide district contact information
- Have a legal description:
- Distances and directions
- Reference to Public Land Survey System (PLSS)
- Lot and Block of Subdivision (if application)
- Combination thereof
- Contain a map:
- Must match legal description
- Reference PLSS
- Lot and block descriptions must include copy of recorded subdivision plat
- Include existing district boundary whenever possible
- North arrow and scale
- Exhibit information with district name and ordinance number
- Bearings and distances between points, if applicable
Please email a copy to ISTC: gis@tax.idaho.gov