Ada County homes are still selling at a steady clip this fall. In September 2026 the median single-family home sold for $575,000, up 2.95% from a year earlier, with 854 sales and about 2.4 months of supply. The real story is the split: resale homes are scarce, while new construction makes up more than half of what's for sale.

That split changes how you should shop, price and negotiate in the Treasure Valley right now. Here's what the numbers from the Intermountain MLS September 2026 Ada County report actually say, and what they mean if you're buying or selling.

What happened to Boise-area home prices this fall?

Prices rose, but slowly. The countywide median of $575,000 compares with $558,545 in September 2025. For the first nine months of 2026 the median was $569,000, up about 1.6% from the same stretch of 2025.

Sales picked up faster than prices did. Ada County closed 854 single-family sales in September, 8.5% more than a year earlier, and 7,711 sales year to date, up about 14%. Median days on market slipped to 39 from 44.

So this isn't a crash and it isn't 2021. It's a market where buyers are active and prices are inching up.

Why does resale vs. new construction matter so much right now?

Because they're behaving like two different markets. In September there were only 955 existing (resale) homes listed in Ada County, down from 1,139 a year ago. That works out to roughly 1.8 months of supply. New construction had 1,051 listings and about 3.6 months of supply.

• Resale median: $561,065, up about 2% from a year earlier
• Resale homes sold: 610, up about 18%
• New construction median: $622,704, up about 10%
• New construction homes sold: 244, down about 10%

If you're shopping resale in an established Boise neighborhood, expect competition for the good listings. If you're looking at new subdivisions in places like Star, Kuna or Meridian, you'll usually have more choices and more time.

What should buyers do differently in this market?

Pick your lane early. A resale buyer and a new construction buyer need different game plans.

For resale, get fully pre-approved before you tour, and be ready to write an offer within a day or two on a well-priced home. With under two months of supply, the clean, move-in-ready houses don't sit.

For new construction, slow down and read the fine print. Builders often offer incentives like rate buydowns or closing cost help, but terms vary a lot by builder and by community, so compare the full package and not just the base price. Ask about HOA dues, lot premiums and what's actually included in the price.

One Idaho detail catches out-of-state buyers. Newly built homes that have never been lived in are exempt from Idaho's seller disclosure law, except for questions about city annexation and city services. That means you won't get the usual seller disclosure form, so a private home inspection matters even more. Our guide to Idaho's seller disclosure rules explains what that form covers.

Is it a good time to sell a house in Ada County?

If you own a resale home in decent shape, the supply numbers lean your way. Resale sales were up about 18% year over year while resale inventory dropped about 16%. That's a seller-friendly mix.

Don't overprice, though. The median only rose about 2% for existing homes, so buyers aren't paying wild premiums. A home priced above recent comparable sales tends to sit, and stale listings usually end up selling for less.

Also keep in mind who you're competing with. A buyer touring your 15-year-old house in Meridian may also be looking at a brand-new home with builder incentives a few miles away. Condition, price and a clear story about upgrades matter.

Are prices the same across the Treasure Valley?

No. A countywide median hides big differences between cities and neighborhoods, and Canyon County runs on its own numbers. A median is the midpoint of what sold, not what any one house is worth.

For your specific home or target neighborhood, look at recent comparable sales within a small radius. A local agent can pull those from the MLS and tell you how fast similar homes actually went under contract.

What costs should new Idaho owners plan for after closing?

Your purchase price is only the start. Idaho property tax depends on where you live, and owner-occupants should apply for the homeowner's exemption, which can take up to $125,000 off the taxable value of a primary home. See our article on the Idaho homeowner's exemption deadline for new buyers for how and when to file.

If you're moving here and switching health coverage too, open enrollment runs through December 15. Our piece on Idaho's 2027 health insurance rate changes covers what to check, and the Idaho insurance hub has more.

FAQ

What was the median home price in Ada County in September 2026?

According to the Intermountain MLS, the median single-family sale price in Ada County was $575,000 in September 2026, up about 3% from September 2025. Resale homes had a median of $561,065, and newly built homes had a median of $622,704.

How much housing inventory does Ada County have?

In September 2026 Ada County had 2,006 active single-family listings, about 2.4 months of supply. Only 955 were resale homes, roughly 1.8 months of supply, while 1,051 were new construction, about 3.6 months.

Are Boise-area homes selling quickly?

Fairly quickly. The median days on market for all Ada County single-family homes was 39 in September 2026, and resale homes went under contract in a median of 35 days. New construction took longer, at a median of 48 days.

Do I get a seller disclosure form on a new build in Idaho?

Usually not. Idaho exempts newly constructed homes that have never been lived in from the full seller disclosure form, though builders must still answer questions about city annexation and city services. Get your own inspection.

Next step

Market averages only go so far. A licensed local real estate agent can pull recent sales for your exact neighborhood, explain how resale and new construction compare where you're looking, and help you set a price or offer that fits this fall's market.

Source: Intermountain MLS, Ada County Single Family Home Sales, September 2026 report (data via Boise Regional REALTORS).

If you bought and moved into an Idaho home in 2026, apply for the homeowner's exemption with your county assessor by the close of business on the last business day of the year, which is Thursday, December 31, 2026. It exempts 50% of your home and up to one acre of land from property tax, capped at $125,000.

It doesn't happen automatically. The exemption doesn't transfer with the house, and the title company doesn't file it for you. If you closed this year, especially if you're new to Idaho, this is worth fifteen minutes before the holidays.

What is the Idaho homeowner's exemption?

It's a property tax break for owner-occupied primary homes, set out in Idaho Code 63-602G. According to the Idaho State Tax Commission, it exempts 50% of the value of your home and up to one acre of land, up to a maximum of $125,000. That cap has been $125,000 since 2021.

A quick example. If your house and lot are assessed at $500,000, half would be $250,000, so the $125,000 cap applies and your taxable value drops to $375,000. On a $200,000 home, the full 50% ($100,000) would come off.

It also unlocks another credit. Under House Bill 292, passed in 2023, Idaho sets aside a share of state sales tax for homeowner property tax relief, and Ada County says homes that qualify for the homestead exemption by the second Monday in July get that credit on their tax bill without a separate application.

Who qualifies?

You have to own the home and live in it as your primary residence. Houses and manufactured homes both count. Rentals and second homes don't.

Ada County's assessor lists a few practical requirements:

• Own and occupy the home on or before the last county business day in December
• Provide your full name, date of birth, address and previous address
• Provide your Idaho driver's license or Idaho ID number

If you just moved here and don't have an Idaho license yet, Ada County says you can still apply but must supply the Idaho license or ID number within 90 days of applying, or the exemption is denied. So don't put off that trip to the DMV.

What's the deadline for 2026?

For the current tax year, file by close of business on the last business day of the year. In 2026 that's December 31. Elmore County, for example, lists 5:00 p.m. on December 31.

There's good news for late filers. In 2026 the Legislature passed House Bill 843, and the Tax Commission's guidance says the exemption is no longer prorated by when you apply. If you qualify and file by year end, you get the full exemption for 2026.

If you apply after the second Monday in July, the full value may stay on the assessment roll, but the guidance says the county cancels the tax equal to the exemption you'd have received. The result is the same savings. The paperwork just looks different.

This is a separate deadline from Idaho's Property Tax Reduction program, sometimes called the circuit breaker. That program has an April 15 deadline and is for qualifying homeowners who are 65 or older, disabled, widowed or meet other conditions, with income limits.

How do you apply?

You apply with the assessor in the county where the home is, not with the state. Each county handles it a little differently.

• Ada County takes applications through an online form, or by mail, email or in person at 190 E. Front Street, Suite 107, in Boise.
• Elmore County says its applications aren't available online or through title companies.
• Other counties post forms on their assessor's website or at the office.

The Idaho State Tax Commission's homeowner's exemption page explains the rules and points you to county assessors. Keep a copy of what you submit and note the date.

Do you have to reapply every year?

No. Once it's approved, it stays in place until ownership changes or the home stops being your primary residence. You don't refile each year.

You do have to apply again if something changes. Ada County lists moving, adding or removing an owner, and transferring the home into a trust as changes that need a new application.

And if you had the exemption on your old Idaho home, HB 843 guidance says that older exemption is removed the year after the new one is granted. You can't keep both.

What should sellers and buyers watch at closing?

Property taxes in Idaho are usually prorated between buyer and seller at closing, based on the current bill. If the seller had the exemption and you don't file, your future bills can come in higher than the number you saw at closing.

Sellers moving within Idaho should file at the new home as soon as they move in. Buyers relocating from out of state should get the Idaho license sorted early, since the 90-day ID rule can sink an otherwise valid application.

While you're dealing with paperwork, check whether your new address sits in a mapped flood zone on FEMA's Flood Map Service Center, since it matters for insurance. FloodFireCheck explains how to read FEMA flood data in plain English. If you're new to the state and still sorting out coverage, see our guide to Idaho's 2027 health insurance changes, and if you're shopping for a home, read our look at the Boise-area housing market this fall.

FAQ

How much does the Idaho homeowner's exemption save?

It removes 50% of the assessed value of your primary home and up to one acre of land from property tax, up to $125,000. Your actual dollar savings depend on your local tax levy, which varies by county, city and taxing district.

Can I still get the exemption if I closed on my home in November or December?

Yes. You need to own and occupy the home and file with your county assessor by close of business on the last business day of the year. Under the 2026 law change, a qualifying application filed by then gets the full exemption.

Does the homeowner's exemption carry over from the seller?

No. It's tied to the owner who lives in the home. A new owner has to file a new application with the county assessor.

Do I need an Idaho driver's license to apply?

You need to provide an Idaho driver's license or Idaho ID number. If you've lived in Idaho fewer than 90 days and don't have one yet, counties like Ada let you apply and then provide the number within 90 days.

Next step

If you're buying or just bought, a licensed local real estate agent can walk you through how property taxes were prorated at closing, point you to the right county assessor, and flag anything else new Idaho owners tend to miss in their first year.

Sources: Idaho State Tax Commission homeowner's exemption page and April 7, 2026 HB 843 guidance memorandum; Ada County Assessor; Elmore County Assessor; Idaho State Tax Commission April 7, 2026 press release.

In Idaho, a seller of a home with one to four units must give the buyer a signed seller property disclosure form within 10 days after accepting the buyer's offer. If the buyer gets it after signing the purchase contract, the buyer has three business days to back out in writing over a specific item on the form.

That's the core of the Idaho Property Condition Disclosure Act, Idaho Code 55-2501 and the sections after it. Below is what the form covers, what it leaves out, and how the deadlines play out for buyers and sellers.

What does an Idaho seller have to disclose?

The statute prescribes a short form. The seller answers what they actually know about the property, including:

• Whether the property is in an area of city impact or receives city services, making it subject to annexation
• Whether included appliances and systems work, and any that don't
• Problems with basement water, foundation, roof condition and age, well, septic, plumbing, drainage, electrical and heating
• Anything that could affect clear title, such as encroachments, easements, zoning violations or lot line disputes
• Known hazardous materials or pest infestations
• Additions or alterations made without a building permit
• Any other known legal or physical problems

The law also says the form isn't a warranty and isn't a substitute for an inspection. The seller is only describing what they know in good faith.

When does the seller have to deliver it?

Within 10 days of accepting the buyer's offer, under Idaho Code 55-2509. The buyer then acknowledges receipt by signing and dating a copy and delivering it back to the seller or the seller's agent.

Many sellers fill the form out at listing time, and some listings post it in the MLS before any offer comes in. Idaho REALTORS' legal hotline has warned that this practice can blur when the buyer actually "received" the form, which matters for the rescission clock. If you're a buyer, make sure the date you received the disclosure is written down clearly.

Can an Idaho buyer back out after reading the disclosure?

Yes, within limits. Under Idaho Code 55-2515, a buyer who receives the form or an amendment after signing the purchase agreement can rescind. The rules are strict:

• The notice must be in writing, signed and dated
• It must name the specific disclosure the buyer objects to
• It must be delivered to the seller or the seller's agent within three business days of receiving the form

If the buyer rescinds properly, the seller has to return the buyer's deposits, and the buyer has no legal liability for backing out. Miss the three-day window and the right is waived.

If the seller later amends the form, the buyer's right to rescind applies only to the amended items. And sellers must amend before closing if they learn something on the original form has changed.

Which sales are exempt from Idaho's disclosure law?

Idaho Code 55-2505 lists 16 exemptions. The ones buyers run into most:

• New construction that's never been lived in, though builders must still answer the annexation and city services questions
• Foreclosures and sales by a lender after foreclosure or a deed in lieu
• Estate and trust sales by a fiduciary, and transfers from a decedent's estate
• Court-ordered transfers, including bankruptcy and probate
• Family transfers, such as to a spouse or children, and between co-owners

If you're buying one of these, you may not get a disclosure form at all. Plan on a thorough inspection and more of your own research. On a new build this is the norm, which is one reason we flagged it in our look at the Boise-area housing market this fall.

What doesn't the Idaho form ask about?

This is where buyers should pay attention. The statutory form doesn't have a specific line asking about flood zone status or wildfire risk. It asks about drainage and basement water, but a dry basement says nothing about whether the lot sits in a mapped floodplain.

So check it yourself before your inspection deadline, since flood zone status can drive insurance costs. Look up the address on FEMA's Flood Map Service Center, and if flood zones are new to you, FloodFireCheck explains FEMA flood data in plain English. Homes near forest edges or in the foothills deserve questions about wildfire risk too, since the form won't raise them.

Also ask about anything the form only touches lightly. Well and septic details matter a lot on rural Idaho property. Permits matter on older homes with finished basements or additions.

What happens if a seller leaves something out?

Under Idaho Code 55-2517, a seller who willfully or negligently fails to meet the law's duties is liable for the buyer's actual damages. Sellers aren't liable for errors outside their personal knowledge, or for errors based on information from public agencies or experts that was obtained with ordinary care.

The act doesn't let sellers off the hook for anything else they're required to disclose, and it doesn't reduce what a real estate licensee owes clients. If you're a seller, answer honestly and update the form if something changes. If you're not sure how to answer a question, say what you know and talk to a professional rather than guessing.

FAQ

How long does an Idaho seller have to give the disclosure form?

The seller must deliver a signed and dated property disclosure form within 10 days of accepting the buyer's offer, under Idaho Code 55-2509. The buyer acknowledges receipt by signing, dating and returning a copy.

How many days does a buyer have to cancel after getting the disclosure in Idaho?

Three business days from receiving the form, if it arrives after the purchase agreement is signed. The written notice has to identify the specific disclosure the buyer objects to, and the buyer gets their deposit back.

Do Idaho builders have to provide a seller disclosure?

Not the full form. Newly built homes that have never been occupied are exempt, but the builder still has to disclose whether the property is subject to city annexation or receives city services.

Does the Idaho disclosure form cover flood risk?

Not directly. It asks about drainage and basement water but has no specific flood zone question. Buyers should look up the address on FEMA's flood maps and ask about wildfire exposure on their own.

Next step

Disclosure deadlines are short, and the right response depends on what the form says and when you got it. A licensed local real estate agent can track those dates for you, help you read the seller's answers, and explain how the homeowner's exemption works once you move in, and line up the inspections that fill in the gaps.

Source: Idaho Property Condition Disclosure Act, Idaho Code Title 55, Chapter 25; Idaho REALTORS Legal Hotline.