Last updated 2026-07-09
TL;DR
The Ada County Assessor values all taxable property as of January 1 each year. Notices go out by June 1. You have until the fourth Monday of June (June 23, 2025) to file a written appeal with the Board of Equalization. The homeowner's exemption cuts taxable value by 50%, up to $125,000. Every step is doable yourself, no contingency firm needed.
What does the Ada County Assessor actually do?
The Ada County Assessor puts a market value on every parcel in the county as of January 1 each year. That's the job. The number feeds straight into your tax bill, because your property tax equals your taxable value times whatever levy rate your local taxing districts set.
The assessor does not set the tax rate. The assessor does not collect a dime. Those jobs belong to the Ada County Commissioners, who approve budgets, and the Ada County Treasurer, who bills and collects. [1]
The office also runs the county parcel database, processes exemption applications, and mails the annual assessment notice every homeowner dreads. Ada County covers Boise, Meridian, Eagle, Kuna, and Star, and it's the most populous county in Idaho. [2]
If your assessment jumped, the assessor's office is your first call. If that call goes nowhere, the Board of Equalization is next. Knowing which office does what keeps you from wasting an afternoon complaining to the wrong people.
How does Ada County calculate your assessed value?
Idaho law requires property to be assessed at 100% of market value. The assessor uses mass appraisal, which means staff analyze large groups of similar properties using sales, cost, and income data instead of walking through every home one at a time. [3]
For houses, the workhorse is the sales comparison approach. The office pulls arm's-length sales from roughly the 18 months before January 1, adjusts for size, age, condition, and location, then applies the pattern across similar homes. If sales near you rose 15% last year, expect your assessed value to move about that much.
Commercial and income property gets the income approach layered on, using market rent and capitalization rates. New construction gets the cost approach: what it costs to build today, minus depreciation.
Here's the part homeowners miss. The value on your notice is the market value estimate. Your taxable value is a different, lower number once the homeowner's exemption comes off. Read both lines.
What is the homeowner's exemption in Ada County and how much does it save?
Idaho's homeowner's exemption is one of the better primary-residence breaks in the West. Under Idaho Code 63-602G, if the home is your primary residence and you own it as of January 1, you can exempt 50% of the assessed value, capped at $125,000. [4]
The statute puts it plainly: the exemption applies to "the lesser of fifty percent (50%) of the market value for assessment purposes of the homestead or the maximum amount."
Say your home is assessed at $400,000. Half would be $200,000, but the cap holds it to $125,000, leaving a taxable value of $275,000. At a combined levy near 1% (rates vary by taxing district), that exemption saves you roughly $1,250 a year.
The cap adjusts annually for inflation under the Idaho Housing Price Index. It rose to $125,000 effective January 1, 2023. [4]
You apply once with the Ada County Assessor's office. After that it stays on your account as long as the home is your primary residence. No annual re-filing. If you bought recently and never applied, look at your notice. The exemption line shows either a dollar amount or a zero. A zero means you're probably overpaying right now.
Other exemptions worth knowing:
- Circuit breaker (Property Tax Reduction Program): for qualifying low-income seniors, disabled residents, and disabled veterans. Cuts taxes by $150 to $1,500 depending on income. Deadline is April 15. [5]
- Veterans property tax reduction: 100% service-disabled veterans can exempt the house and up to one acre. Surviving spouses may qualify too. [5]
- Agricultural land: assessed at use value instead of market value under Idaho Code 63-604. [3]
When does Ada County mail assessment notices and what are the key deadlines?
This is where most homeowners lose the appeal before they start. Miss the deadline by one day and you're out for the year. No extensions.
| Event | Typical Date |
|---|---|
| Assessment lien date (valuation as of) | January 1 |
| Assessment notices mailed | By June 1 |
| Appeal filing deadline (Board of Equalization) | 4th Monday of June (June 23, 2025) |
| Board of Equalization hearings | July |
| Board of Equalization decision deadline | July 31 |
| Appeal to State Board of Tax Appeals | Within 30 days of BOE decision |
| Appeal to District Court | Within 91 days of BOE decision |
The fourth Monday of June is fixed by Idaho Code 63-501A. In 2025 that's June 23. In 2026 it shifts, so confirm the exact date with the Ada County Assessor's office or the Board of Equalization every year. [9]
The notice itself prints the deadline on it. Read it the day it lands. The office mails to the address on file, so if your mailing address differs from the property address, make sure they have the right one. Plenty of appeals die because the owner never saw the notice.
How do you file an appeal with the Ada County Board of Equalization?
Filing is simpler than most people expect. You submit a written appeal (the office calls it a "petition") to the Ada County Board of Equalization before the June deadline. Grab the form on the Ada County Assessor's website or pick one up at 190 E. Front Street, Suite 107, Boise, ID 83702. [1]
The petition wants your parcel number (it's on the notice), the value you think is correct, and a short reason. No lawyer required. The BOE is the three Ada County Commissioners sitting in a quasi-judicial role. [10]
After you file, the board schedules a hearing, usually in July. You show up, an assessor's office representative shows up, and both sides present. It's informal. Bring photos, a recent independent appraisal, or comparable sales printouts. The board issues a written decision by July 31.
If the BOE rules against you, or trims your value less than you think is fair, you have two more paths:
1. The Idaho State Board of Tax Appeals (SBTA). File within 30 days of the BOE decision. The filing fee is modest; the SBTA can confirm the current amount. Three appointed members hear the evidence fresh, independent of the county. [6] 2. District Court. File within 91 days of the BOE decision. This one usually needs a lawyer and real money, so most homeowners stop at the SBTA.
Before the hearing, build your evidence file. The TaxFightBack DIY appeal kit walks through picking comps and running the actual presentation without paying a contingency cut.
One practical note: bring three copies of everything. One for you, one for the board, one for the assessor's rep. It signals you're organized and moves the hearing along faster.
What evidence actually wins an Ada County property tax appeal?
The assessor has to defend their value. Your job is to show it's wrong with paper. Here's the evidence that carries weight at the BOE, ranked:
1. A recent fee appraisal from a licensed Idaho appraiser. Got one for a refinance or purchase in the past 12 months that came in below the assessed value? Bring it. This is your single strongest piece.
2. Comparable sales. Pull three to five arm's-length sales of homes like yours (same neighborhood, similar square footage, similar age and condition) that closed before January 1 of the tax year. The Ada County Assessor's parcel search shows sales data. Zillow and Redfin can supplement, but county records carry more weight in the room.
3. Errors in the property record. The office keeps a record card on your home. Request it. If it lists 3 bathrooms and you have 2, or counts an unfinished basement as finished square footage, that error is padding your value. Document it with photos and measurements.
4. Uniformity. If comparable homes on your street are assessed lower per square foot than yours, that's an equity argument. Idaho courts have long held that assessments must be uniform across similar properties.
What flops: general gripes that taxes are too high, national housing headlines, and stories about what a neighbor paid. The board wants numbers tied to your parcel.
Other high-growth metros run the same playbook. The methods in Maricopa County, Arizona and San Diego County rest on the same logic: find the comps, catch the errors, make the board do the math.
How much have Ada County assessments risen in recent years?
Ada County has been one of the hottest housing markets in the country since 2020. The Idaho State Tax Commission publishes annual ratio studies that measure how close assessors' values sit to actual sale prices. A ratio near 100% means values track the market closely. [7]
The commission's 2023 ratio study put Ada County's median assessment ratio at about 96%, meaning the typical assessed value ran roughly 96% of the actual sale price. That lands inside the accepted target range of 95 to 105%. [7] It also means some individual properties sat well above or below true market value, and those outliers are exactly what an appeal fixes.
Boise metro home prices rose roughly 40% between 2020 and 2022 by Federal Housing Finance Agency data, then softened in 2023 before leveling off. [8] If your value got set at the peak and your specific neighborhood has cooled since, that gap is worth documenting with recent comps.
The chart below tracks the homeowner's exemption cap over time, which shows how the state has tried to keep the primary-residence break moving with prices.
How does Ada County compare to other fast-growing county assessors?
Ada County isn't unique. Fast-growing counties across the Sun Belt and Mountain West all ran the same sequence: rapid appreciation, assessments catching up on a lag, then homeowner sticker shock and a wave of appeals.
The process mechanics change by state. The evidence strategy does not. In Gwinnett County, Georgia, homeowners face a similar summer deadline and an informal board. In Bexar County, Texas, the Appraisal Review Board plays the part Ada County's BOE plays. Even Baldwin County, Alabama, operating under Alabama's separate classification system, leans on comparable sales at its core.
The lesson from every one of them is the same. Homeowners who win show up with paper: specific sales, specific dates, specific dollar amounts. Homeowners who lose show up with frustration and nothing to hand the board.
For reference across a few systems:
| County | State | Appeal deadline | Informal hearing? | Exemption cap |
|---|---|---|---|---|
| Ada County | Idaho | 4th Monday, June | Yes (BOE) | $125,000 HO exemption |
| Maricopa County | Arizona | 60 days after notice | Yes (assessor) | $3,965 primary res. credit |
| Gwinnett County | Georgia | 45 days after notice | Yes (BOE) | $4,000 county homestead |
| Bexar County | Texas | May 15 or 30 days after notice | Yes (ARB) | $100,000 homestead |
Sources: respective county assessor offices and state statutes. Amounts and dates shift by year, so confirm directly before you rely on them.
How do you look up your Ada County parcel and property record?
The Ada County Assessor runs a public parcel search at adacounty.id.gov/assessor. Search by address, parcel number, or owner name. The record shows: [1]
- Current assessed value (land and improvements)
- Exemptions applied (homeowner's exemption, circuit breaker)
- Property characteristics (square footage, year built, bathroom count, lot size)
- Recent sales history
- Tax history
Spend your time on the property characteristics before any appeal. Print or screenshot the record. Then walk your house with the printout in hand. Any error you catch (wrong square footage, a phantom bathroom, finished space that's actually unfinished) is money back if you document it.
You can also request the full property record card, which shows more detail than the public portal. Call 208-287-7200 or stop by 190 E. Front Street, Suite 107, Boise, ID 83702.
What happens after the Board of Equalization rules?
If the BOE cuts your value, that lower number gets certified to the county and your tax bill reflects it. The treasurer recalculates. If you already paid at the higher amount, the overpayment gets credited to next year or refunded, depending on timing.
If the board denies you, or the reduction feels too small, the Idaho State Board of Tax Appeals is worth a serious look. The SBTA runs independent of Ada County, holds its own evidentiary hearing, and can set a final value. For residential cases it's historically been accessible and informal. Forms and instructions are at tax.idaho.gov/sbta. [6]
District Court is the last stop and rarely pays off for a typical home unless the dollars are large. Filing fees, discovery, and attorney fees can swallow any tax savings on a median-priced house.
Here's the math homeowners forget. A $30,000 reduction in assessed value at a 1% blended rate saves $300 a year, every year the corrected value holds. Over five years that's $1,500, before any future appreciation. Worth an afternoon of prep.
The TaxFightBack DIY appeal kit covers the post-hearing steps, including what to do when the BOE only half agrees and whether the SBTA is worth the extra filing.
What are the most common mistakes homeowners make in Ada County appeals?
Missing the deadline is the most common mistake and the most expensive one. No extension, no grace period, no sympathy if you walk in on June 24. Set a calendar reminder the day your notice arrives.
Second: showing up without comps. The board has heard "my house isn't worth that" thousands of times. What earns attention is a spreadsheet with five nearby sales, all lower per square foot than the assessor's implied value for your home.
Third: skipping the property record card. If the office has bad data on your house, you need to find out before the hearing, not while you're standing in front of the board.
Fourth: leaning on a Zestimate or Redfin estimate. Automated valuation models have known accuracy problems, especially in fast-moving markets. The FHFA has documented that AVM accuracy slips in low-transaction periods. [8] Bring real sales, not an algorithm's guess.
Fifth: arguing the tax rate instead of the value. The board can only change the assessed value. It can't touch the levy rate. If your value is accurate and you think the rate is too high, that's a different fight, and it's with the commissioners at budget time.
Got commercial or investment property? The income approach adds a layer. Owners of rental or commercial property should see how other large-county commercial appeals run, like the Cook County commercial appeal process.
Frequently asked questions
What is the Ada County Assessor's office phone number and address?
The Ada County Assessor's office is at 190 E. Front Street, Suite 107, Boise, ID 83702. The phone number is 208-287-7200. Office hours are generally Monday through Friday, 8 a.m. to 5 p.m. Mountain Time. You can also reach the office through the parcel search portal at adacounty.id.gov/assessor. Call ahead to confirm hours, especially near the June appeal deadline when call volume spikes.
When is the Ada County property tax appeal deadline in 2025?
The 2025 deadline to file an appeal with the Ada County Board of Equalization is June 23, 2025, the fourth Monday of June. This date is set by Idaho Code 63-501A. Your written petition must reach the BOE by the close of business that day. Postmarks don't count. Hand-deliver or submit early if you're anywhere near the deadline.
How do I apply for the Ada County homeowner's exemption?
File a one-time application with the Ada County Assessor's office before April 15 of the first year you want it. You have to show the property is your primary residence as of January 1. The exemption then renews automatically each year. If you bought mid-year and applied too late, file again in January of the next year. It's worth up to $125,000 off your assessed value under Idaho Code 63-602G.
What is the difference between assessed value and taxable value in Ada County?
Assessed value is the assessor's estimate of market value at 100%. Taxable value is what's left after exemptions come off. For a home assessed at $400,000 with the homeowner's exemption, taxable value drops to $275,000, because the exemption caps at $125,000. Your tax bill runs on the taxable value, not the assessed value. Both numbers print on your annual assessment notice.
Can I appeal my Ada County property taxes if I missed the June deadline?
No. Idaho is strict here. Miss the fourth Monday of June to file with the Board of Equalization and you can't appeal that year's assessment. Your only move is to wait for next year's notice and file on time. One narrow exception: if you can prove you never got the notice because the assessor had a wrong mailing address, ask an Idaho property tax attorney whether a late filing might be considered. It's rare and not guaranteed.
How does the Ada County Board of Equalization hearing work?
After you file your petition, the BOE schedules a hearing in July. It's informal, in front of the three Ada County Commissioners. You present your evidence (comps, appraisal, record errors), the assessor's rep responds, and the board asks questions. Residential hearings usually run 15 to 30 minutes. The board issues a written decision by July 31. You can bring an attorney, but most homeowners handle it themselves and do fine.
What is the Idaho State Board of Tax Appeals and how do I file there?
The Idaho State Board of Tax Appeals (SBTA) is an independent three-member board that hears property tax appeals after the county BOE process. You file within 30 days of the BOE's written decision. The SBTA holds a de novo hearing, meaning it reviews the evidence fresh. Forms and instructions are at tax.idaho.gov/sbta. This is the practical next step if the BOE denies you, and it costs far less than District Court.
Does Ada County reassess property every year?
Yes. Idaho law requires annual reassessment. The Ada County Assessor values all property as of January 1 every year, so your assessed value can rise or fall each year depending on local sales data. In practice the office uses mass appraisal models recalibrated annually with recent sales, so your value tracks the market, sometimes with a slight lag in fast-moving years.
What is the circuit breaker property tax reduction program in Ada County?
Idaho's Property Tax Reduction Program, the circuit breaker, cuts property taxes by $150 to $1,500 for qualifying low-income seniors (65 and older), disabled residents, surviving spouses, and some veterans. Income limits apply and change annually. The deadline is April 15 at the Ada County Assessor's office. It's separate from the homeowner's exemption, and plenty of eligible homeowners have no idea it exists.
How do I find comparable sales to use in my Ada County appeal?
Use the Ada County Assessor's public parcel search at adacounty.id.gov/assessor to pull recent sales by neighborhood or subdivision. Look for arm's-length sales (not foreclosures, estate sales, or related-party transfers) that closed in the 12 to 18 months before January 1 of the tax year. Pick homes like yours in square footage, age, condition, and lot size. Three to five good comps showing a lower per-square-foot value than your assessment is usually enough to win.
What if my Ada County property has errors in the assessor's records?
Request your property record card from the Ada County Assessor's office at 208-287-7200 or in person. Compare it to your actual home. Common errors: wrong square footage (often counting an unfinished basement as finished), extra bathrooms, incorrect garage size, wrong year built. Photograph the real condition, take measurements, and present the discrepancy at your BOE hearing. Factual errors are among the easiest appeals to win.
Is it worth hiring a property tax consultant for an Ada County appeal?
For most homeowners, no. The BOE process is informal and built for self-representation. Contingency firms typically take 25 to 50% of your first-year savings, which can wipe out the benefit of a modest reduction. A consultant makes sense for large commercial properties with complex income valuations, or cases headed to District Court where you genuinely need a lawyer. For a typical single-family home, solid comps and a clean record card are enough.
How does the Ada County Assessor value new construction?
New construction gets the cost approach: the assessor estimates what it would cost to build the structure at current material and labor prices, then subtracts depreciation. Land is valued separately using comparable land sales. If you built custom, the assessor will likely use your building permit records and may inspect. If the cost approach produces a value above what comparable finished homes are selling for, you can argue the sales comparison approach should control.
Sources
- Ada County Assessor's Office, official website: Ada County Assessor office address, phone (208-287-7200), parcel search tool, and assessment notice information
- U.S. Census Bureau, QuickFacts: Ada County, Idaho: Ada County is the most populous county in Idaho, including cities such as Boise, Meridian, Eagle, Kuna, and Star
- Idaho Legislature, Idaho Code Title 63 (Property Taxes): Idaho Code 63-604 governs agricultural land use value assessment; Idaho law requires assessment at 100% of market value
- Idaho Legislature, Idaho Code 63-602G (Homeowner's Exemption): Homeowner's exemption equals the lesser of 50% of market value or the maximum amount of $125,000, adjusted annually by Idaho Housing Price Index; effective January 1, 2023
- Idaho State Tax Commission, Property Tax Reduction and Veterans programs: Circuit breaker (Property Tax Reduction Program) reduces taxes by $150 to $1,500 with an April 15 deadline; veterans property tax reduction available to 100% service-disabled veterans
- Idaho State Board of Tax Appeals: The SBTA is an independent three-member board; appeals filed within 30 days of the BOE decision; holds de novo hearings
- Idaho State Tax Commission, Annual Ratio Study 2023: Ada County median assessment-to-sales ratio was approximately 96% in the 2023 ratio study; acceptable range is 95-105%
- Federal Housing Finance Agency, House Price Index: Boise metro area home prices rose approximately 40% between 2020 and 2022; FHFA also documents AVM accuracy degradation in low-volume markets
- Idaho Legislature, Idaho Code 63-501A (Board of Equalization procedures): The appeal filing deadline is the fourth Monday of June; Board of Equalization decisions must be issued by July 31
- Ada County Board of Commissioners (Board of Equalization information): The Ada County Board of Equalization is composed of the three county commissioners; hearings held in July
- Idaho State Tax Commission, Property Tax Overview: Ada County Assessor values property annually as of January 1; assessment notices must be mailed by June 1 under Idaho law