Ada County, ID Property Tax: $2,643/yr (2026)
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The effective property tax rate in Ada County is 0.56% of assessed home value. On a home at the county median value of $476,000, that works out to about $2,666 per year, or $222 per month. Ada County is located in central Idaho, and is home to approximately 508,052 residents.
About Ada County
Ada County covers approximately 1,052.2 square miles in Idaho. The county is home to about 508,052 residents living in roughly 205,068 housing units, of which 68.4% are owner-occupied. The median household income is $88,907, and the median home was built in 1996.
Ada County borders Boise County, Canyon County, Elmore County, Gem County, Owyhee County — useful comparisons if you're considering nearby areas with potentially different tax rates.
How Property Taxes Work in Idaho
Property taxes in Idaho are administered at the county level. Each county sets a millage rate applied to the assessed value of real property — the effective rate above accounts for any partial assessments and exemptions already built into the local tax base. Assessed value can differ meaningfully from current market value depending on how often the county reassesses and what fraction of market value it uses.
Most counties in Idaho offer exemptions that reduce the taxable assessed value: homestead exemptions for primary residences, senior exemptions, disability exemptions, and veteran exemptions are common. These reduce your effective rate below the county-wide average shown here. Contact the Ada County Assessor's office to learn which exemptions apply to your property and when to file.
Ada County vs. Neighboring Counties
| Location | Eff. Rate | Median Home | Annual Tax |
|---|---|---|---|
| Ada County, ID | 0.56% | $476,000 | $2,666 |
| Idaho state average | 0.51% | — | $2,428* |
| Boise County | 0.37% | $424,100 | $1,571 |
| Canyon County | 0.57% | $350,300 | $1,996 |
| Elmore County | 0.60% | $278,300 | $1,680 |
| Gem County | 0.39% | $367,300 | $1,443 |
| Owyhee County | 0.48% | $281,600 | $1,355 |
| US national average | 1.10% | $281,900 | $3,101 |
*State average annual tax computed at Ada County's median home value of $476,000. Source: US Census ACS 2023 5-year estimates.
Frequently Asked Questions
How does Ada County's property tax rate compare to the rest of Idaho?
At 0.56%, Ada County is higher than the Idaho state average of 0.51%. On a home at the county median of $476,000, that means about $2,666 per year — versus $2,428 at the state average rate, a difference of $238 per year. Compared to the national average of 1.10%, Ada County is below average.
What's a typical annual property tax bill in Ada County?
For a home at the county median value of $476,000, the annual property tax in Ada County is approximately $2,666 — or about $222 per month. For a home worth $714,000, expect around $3,998 per year. For a $952,000 home, approximately $5,331 per year. Use the calculator above to estimate taxes for any assessed value.
Where do I appeal a Ada County property tax assessment?
Property assessment appeals in Ada County are handled by the Ada County Assessor's office. Most jurisdictions require filing within 30–90 days of receiving your assessment notice — confirm the specific deadline with the assessor's office before submitting, as deadlines and procedures vary by county. A successful appeal can reduce your assessed value and lower your tax bill for the current and future tax years.
What exemptions are available in Ada County?
Idaho counties commonly offer homestead exemptions for owner-occupied primary residences, senior citizen exemptions for qualifying homeowners aged 65 and older, exemptions for disabled residents, and veterans' exemptions. Each exemption reduces your assessed taxable value, which in turn reduces your effective tax rate below the county-wide 0.56% shown here. Contact the Ada County Assessor's office to confirm which exemptions are available and the application deadlines.
Data sources: US Census Bureau ACS 2023 5-Year Estimates, US Census Gazetteer (2024), County Adjacency File