"DuPage County will publish only those Milton Township 2026 assessments that have changed for a reason other than the 7.17% County Equalization Factor." That sentence comes from the Milton Township Assessor's office, which publishes its assessment changes in the Wheaton and Glen Ellyn Suburban Life papers. The same page says the 7.17% factor applies to all property assessments in the township.
So nearly every home in Milton Township has a higher 2026 assessed value than it had a year ago. If the only change was the factor, the owner got no Change of Assessment Notice and the home did not appear in the October 9 legal publication. The DuPage County assessment status page describes the same practice countywide. Notices and publication cover only parcels whose values changed for some reason other than the township-wide factor.
For a buyer comparing homes in DuPage right now, the tax figure on a listing describes a house as it was assessed a year ago.
The tax line you see this month is already out of date
Illinois bills property taxes in arrears. According to the DuPage County Treasurer, the 2025 tax bills, 321,773 of them, went out on April 29, 2026, with installments due June 1 and September 1, 2026. No newer bill exists. Any tax figure a buyer sees during a home search this November comes from the 2025 assessment.
The 2026 assessment has already replaced it. The county's assessment cycle page says the bills built on it usually go out during the last week of April in the year after the assessment year, which means late April 2027, with the first installment usually due June 1 and the second September 1. A buyer who closes this winter will pay that first 2027 bill on a value that rose this fall, even though the paperwork they compared homes with never showed it.
Nine townships got nine different raises
The factor is calculated separately for each township. The county's Supervisor of Assessments measures how assessed values compare with a three-year history of sales in each township. If assessments fall short of the statutory level, it multiplies every parcel there by the same number to close the gap. The statutory target is one-third of market value. The factor applies to both the land and the building portion of each assessment.
Here is how 2026 turned out, from the county's status table:
| Township | 2026 factor | Increase | Published | Board of Review deadline |
|---|---|---|---|---|
| Bloomingdale | 1.0793 | 7.93% | Sept. 25 | Oct. 26 |
| Milton | 1.0717 | 7.17% | Oct. 9 | Nov. 9 |
| Winfield | 1.0676 | 6.76% | Oct. 23 | Nov. 23 |
| Naperville | 1.0676 | 6.76% | Sept. 11 | Oct. 13 |
| Lisle | 1.0669 | 6.69% | Oct. 8 and 9 | Nov. 9 |
| York | 1.0642 | 6.42% | Sept. 3 and 4 | Oct. 5 |
| Downers Grove | 1.0635 | 6.35% | Oct. 1 and 2 | Nov. 2 |
| Wayne | 1.0611 | 6.11% | Aug. 28 | Sept. 28 |
| Addison | 1.0590 | 5.90% | Sept. 11 | Oct. 13 |
As of this Thursday, three of those windows are still open: Milton and Lisle on November 9, and Winfield on November 23. Wayne Township's changes ran in the Carol Stream and West Chicago Suburban Life papers, and Winfield's ran in West Chicago Suburban Life. The county's appeal process page says Board of Review appeals must be filed within 30 days of a township's assessment roll being published. It also says an appeal challenges the assessed value, not the tax bill, and should be supported with evidence from comparable properties.
The spread between townships is about two percentage points, and that gap matters more than any single factor.
Last year, assessments rose 8.2% and bills rose 3.83%
The Treasurer's office published preliminary figures for the 2025 tax year. Countywide, assessed value rose 8.2%, the average tax rate fell 4.37%, and total property tax bills rose 3.83%, on a total levy of $3,756,793,481. The same notice adds that "there is no 'average' bill."
The mechanics explain the gap. Each school district, park district or other taxing body asks for a dollar amount. The County Clerk divides that request by the total taxable value in the district to set the rate, and the Property Tax Extension Limitation Law caps how much some of those bodies can raise their requests. When values rise faster than the requests, the rate falls. An April 30, 2026 DuPage Community News report on the state's multiplier put it this way: "If the amount requested by local taxing districts is not greater than the amount received in the previous year, then total property taxes will not increase even if assessments increase."
So what actually moves an individual bill is the home's share of the total. Each property's assessed value sets its share of a district's levy. If every home in a district rose by the same 7.17%, those shares would stay the same and the factor would wash out of the math. Some districts cross township lines, though, and the same DuPage Community News report notes that school, junior college and fire protection districts can even cross county lines. In a district that covers parts of Bloomingdale and Wayne, the Bloomingdale side went up 7.93% this year and the Wayne side went up 6.11%. That shifts a little more of the shared levy onto the Bloomingdale homes. A buyer weighing a home in Wheaton against one in West Chicago is also comparing how fast each township's sales have pulled its assessments up.
Two different factors share the name "multiplier," and they're easy to mix up. The township factors above come from the county. The state also issues one countywide factor, and for 2025 taxes it was 1.0000, because the Illinois Department of Revenue found DuPage assessments at 33.32% of market value based on 2022 through 2024 sales. A factor of 1.0000 means the state left values where they were, so the year-to-year change came from the county and township side.
Prices are still running ahead of the formula
The township factors rest on a weighted three-year average of sales, so assessed values always trail prices. Prices haven't stopped moving. The Illinois REALTORS DuPage County report for September 2026 shows a median sale price of $444,000 across all property types, up 8.3% from $410,000 in September 2025, with 861 closed sales in both months.
How the September median breaks down matters for assessments. Single-family homes had a median of $538,000, up 4.5% from a year earlier, while condos had a median of $310,000, up 7.9%. A township factor applies the same percentage to a condo and a detached house. If attached homes keep appreciating faster, a flat factor will keep under-adjusting them relative to houses. One month of data doesn't establish a trend, but the next full reassessment is designed to correct that kind of gap.
The market has also loosened a little. In September 2026, DuPage inventory was 1,508 homes, up 13.7% from a year earlier, and homes took 21 days to sell, up from 18. Even so, prices that have already been recorded stay in the three-year window that sets the next assessments.
2027 is when every parcel gets a letter
In years between full reassessments, township assessors revalue only properties that physically changed or that they choose to review individually. The last general assessment years were 2019 and 2023, and in those years the county mailed a change of assessment notice for every parcel. The Bloomingdale Township Assessor lists 2027 as the next quadrennial reassessment. Downers Grove Township's assessor says general reassessments include neighborhood-level adjustments meant to make assessments more uniform.
Using the county's rule that values reflect the three prior years of sales, the 2027 values would presumably draw on sales from 2024 through 2026, including this fall's. For a Milton Township home bought this winter, the tax calendar runs like this:
- Now: The latest bill on record is for 2025 taxes, mailed April 29, 2026.
- November 9, 2026: The Board of Review deadline for 2026 Milton assessments.
- November 15, 2026: The statutory date by which township assessors finish entering the year's values.
- Late April 2027: 2026 bills go out, reflecting the 7.17% factor.
- 2027: A general reassessment, with a notice for every parcel.
- Spring 2028, following the usual pattern: Bills based on the reassessed 2027 values.
A buyer today could hold two property tax bills before the reassessed value shows up in a third.
FAQ
If I didn't get a notice, did my assessment change? In most of DuPage, yes. The factor applies to every parcel in a township, and the county doesn't mail notices for changes caused only by the factor.
Does a 7.17% factor mean a 7.17% higher bill? No. Bills depend on what each taxing body requests and on your home's share of the total taxable value. In the 2025 tax year, assessed value rose 8.2% countywide and total bills rose 3.83%.
Where do I find my township's deadline? The county's assessment status table lists each township's factor, publication date and final filing date. The page updates as the year goes on, so check it directly before relying on a date.
This post is general information, not legal, tax or financial advice. For questions about your own assessment or appeal, talk with your township assessor, the Board of Review, or a tax professional.
Assessments trail sale prices by design, so the assessor's number for a home rarely matches what a buyer would pay for it today. If you'd like to know what your home would sell for this winter, The Lance Kammes Team can price it against recent sales in your township. Get a Free Home Valuation.
