Ada County’s effective property tax rate is approximately 0.76% of market value — among the lower effective rates in the Western United States. Idaho assesses residential property at 100% of market value (unlike Tennessee’s 25% assessment ratio), so the calculation is more straightforward: multiply your home value by approximately 0.0076 to get a rough annual tax estimate before exemptions.
Idaho’s homestead exemption reduces the taxable value of a primary residence by 50% of market value, capped at a maximum reduction of $125,000. The exemption is applied automatically by the Ada County Assessor once you file — but you must file. Once filed for your primary residence, the exemption renews automatically unless ownership changes. You do not need to reapply annually.
The key nuance: the cap means the exemption is proportionally more valuable on lower-priced homes. On a $300,000 home, the 50% of value is $150,000 — but capped at $125,000, saving approximately $950/year. On a $700,000 home, the 50% of value is $350,000 — still capped at $125,000, saving the same approximately $950/year. The cap makes this exemption less progressive than it might appear.
File with the Ada County Assessor’s office. You will need your deed or closing documents confirming you are the owner and the property is your primary residence. Apply within the application window in your first year of ownership. Ada County Assessor: 208-287-7200. File at 190 E. Front Street, Boise, ID 83702.
Idaho’s Circuit Breaker program provides additional property tax relief for homeowners who are 65 and older with qualifying income below the program threshold (approximately $33,220 for the 2026 tax year — verify current limit with the Ada County Assessor). Unlike the homestead exemption, the Circuit Breaker provides a direct dollar credit or deferral against the property tax bill.
The Circuit Breaker is separate from and in addition to the homestead exemption. Buyers at or below the income threshold should apply for both. The combined benefit for qualifying low-income 65+ buyers can reduce Ada County property tax to near-zero on modestly priced homes.
| Factor | Ada County | Canyon County |
|---|---|---|
| Effective rate | ~0.76% | ~0.88% |
| Annual tax — $420K home after exemption | ~$2,395 | ~$2,860 |
| Homestead exemption | 50% up to $125K reduction | 50% up to $125K reduction (same rule) |
| Annual savings from exemption | ~$950 | ~$1,100 |
| Assessor office | Ada County Assessor, Boise | Canyon County Assessor, Caldwell |
| 55+ communities | All Cadence, Willowbrook, Brooke View | Trilogy Valor (Kuna) |
Tell us your target purchase price and we will calculate your Ada County tax bill with and without the homestead exemption.
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