Northbrook's Tax Bills Were Written at the Ballot Box. Closings Are Still Catching Up.

Anyone who bought a Northbrook home between January and late summer 2026 almost certainly closed on a tax proration built from the 2024 bill. Cook County's second-installment bills for tax year 2025 came out about two months late. They went online in mid-August, paper copies were mailed in early September, and payment was due October 1, 2026. Until those bills arrived, the 2024 bill was the only full-year figure available, and it still reflected values from the 2022 reassessment.

Across most of the North Shore, the new bills turned out to be modestly higher. Northbrook's went up more. In its town-by-town review of Treasurer data, the law firm Braverman & Makhlouf found the typical Northbrook single-family bill rose 13.8%, or $1,878, from tax year 2024 to tax year 2025. Among north-suburban Cook County towns, only South Barrington saw a bigger increase. The reassessment did not cause most of that jump. School bond referendums did, and some of that borrowing has not yet shown up on any bill. That second point matters more than anything else for buyers and sellers here.

The Reassessment Lowered Tax Rates Across the Region

The 2025 Cook County reassessment covered 13 north and northwest suburban townships, including Northfield and New Trier. After appeals, residential assessed value in the region rose 24.4%. Rising assessments do not raise bills on their own. Each school district, village and park district sets its levy, and the Cook County Clerk then sets a tax rate that spreads that levy across all property in the district. When values rise everywhere at once, rates fall. Across the north and northwest suburbs, the average rate dropped about 13%, and in Wilmette and Winnetka it fell about 18% and 19%.

Because of that, the reassessment by itself mostly moved the tax burden around within each town rather than raising it. What made Northbrook different was the size of the levies it voted for.

Winnetka's dollar increase was larger because its bills are larger. In percentage terms, Northbrook stands well apart from its neighbors.

Two School Elections on April 1, 2025

On April 1, 2025, voters in Northbrook School District 28 approved $94.9 million in bonds. The district's facilities plan covers work at Greenbriar, Meadowbrook, Northbrook Junior High and Westmoor, including additions, renovations, HVAC, safety and accessibility upgrades, and classroom and cafeteria projects. On the same ballot, voters in Northbrook School District 27 approved a Debt Service Extension Base of $2,655,099. That base supports bonds for roofs, HVAC, electrical work, security systems, parking and drop-off changes at Wood Oaks, and new classrooms at Hickory Point.

Braverman & Makhlouf reports that the amount District 28 billed went up 19% for tax year 2025. The Cook County Treasurer's tax year 2025 bill analysis, published in August 2026, measured the result a slightly different way. It found the median Northbrook homeowner bill rose 13.7% to $13,472 and attributed the increase to the school referendums.

The districts had published their own estimates before the vote. District 28's FAQ projected $621.70 a year for a property valued at $500,000. District 27 estimated about $422 a year for an average $600,000 home. Which district an address falls in determines which of these levies appears on its bill. District 27 describes itself as one of four elementary districts within the Village and serving its northwest segment, and it points residents to a Village address lookup to check their boundaries.

What the Spring Proration Missed

In Cook County, the first installment equals 55% of the prior year's total bill, so the entire year-over-year change lands on the second installment. Here is an illustration using a home whose bill changed by exactly Northbrook's typical single-family amount. A $1,878 increase at 13.8% implies a 2024 bill of roughly $13,609 and a 2025 bill of roughly $15,487.

The second installment came in about 31% higher than a flat-bill estimate would have predicted. Under Paragraph 12 of the Multi-Board 8.0 contract, tax prorations are final at closing unless the parties agree otherwise in writing. A buyer whose credit was based on 100% of the 2024 bill generally absorbs the difference. In this illustration, for a closing at mid-year, the seller's half of that $1,878 comes to roughly $940 that the buyer ends up covering.

Why the 2025 Bill Still Isn't a Full Picture in Northbrook

For closings now, the 2025 bill is the most recent full-year bill available, and it reflects the new assessed values. That makes it a more reliable basis for prorations than the 2024 bill was in the spring. In most north-suburban towns, the story ends there. In Northbrook, the school borrowing is still being issued in stages.

District 28's July 2025 newsletter reported that the first round of bonds sold for $14,550,000, earned an AAA rating with a stable outlook from Standard & Poor's, and would pay for the new Meadowbrook School gymnasium. The board's May 27, 2025 resolution authorized that first issue as part of the $94.9 million approved by voters. District 28 has not published a schedule for later sales or for the levy years they will affect. District 27 says its DSEB structure allows bonds to be issued as specific projects need funding. Its tax page labels the per-home figure as an estimated impact on bills payable in 2026, contingent on the district issuing bonds and levying the full base.

There is also a newer vote. In March 2026, voters in Sunset Ridge School District 29 approved $23.5 million in bonds, 926 to 458, according to The Record North Shore. Superintendent Dr. Ed Stange said the result allows the Middlefork School project to proceed, and the outlet reported a projected cost of about $445 a year for a $500,000 property. District 29's boundaries include a small section of Northbrook. That vote came after the tax year 2025 levies were set. None of these sources says which future bill will first include it.

The tax cap does not limit any of this. For tax year 2026, the state cap holds most districts' levy increases to 2.6%, but payments on voter-approved bonds are exempt. No published source forecasts Northbrook's 2026 bill. What can be said is that, depending on the address, debt approved by voters may reach the bill later than the most recent bill suggests.

Two Seller-Specific Items

Some differences between the seller's bill and the buyer's bill have nothing to do with schools. A seller's senior exemption or senior freeze does not carry over to the buyer, so a bill that reflects those exemptions understates what the buyer will pay. If the seller has an appeal pending, the contract can spell out who receives any refund. As of October 1, 2026, the Assessor's appeal window for Northfield Township had closed and the Board of Review's had not yet opened. The north suburbs will not be reassessed again until tax year 2028, so the 2025 assessment is the starting point for the 2026 and 2027 bills.

How Contracts Account for an Unknown Bill

Illinois closing attorneys have several common ways to handle a bill that is expected to change. Braverman & Makhlouf outlines them in a separate guide to prorations:

• A percentage above 100%. The parties fill in 105% or 110% of the last known bill instead of 100%, and the proration stays final at closing.
• An estimate from published data. The attorney applies the current tax rate and equalization factor to the newest assessed value, with the understanding that rates can still change.
• A re-proration agreement. Both parties agree in writing to recalculate once the actual bill is issued.
• A tax escrow. Funds are held, typically by the title company, and released once the actual bill is known.

This is general information, not legal, tax or financial advice. The right approach depends on your contract and your property, so confirm your situation with your real estate attorney before you sign.

Quick Answers

Did every Northbrook bill go up 13.8%? No. That figure is the typical single-family change. Individual bills depend on how a property's assessment changed compared with others in the same taxing districts, and on which school districts serve the address.

Where can an owner look up their property's details? The Cook County Assessor's address search lists the property's characteristics, and the Treasurer's exemption history search shows which exemptions were applied in past years.

If you're preparing to list or write an offer in Northbrook this fall, we can help you understand what the current bill reflects for that specific address and what it may not include yet, so you and your attorney can settle the proration before the contract is signed. Reach out to The Wexler Gault Group to get a complimentary home consultation.