Wheaton, Illinois
DuPage County commercial property tax appeals
Appeals start with the DuPage County Supervisor of Assessments, with the nine township assessors and go to the DuPage County Board of Review. Here is how commercial evidence is built, filed and heard in DuPage County.
- Assessor
- DuPage County Supervisor of Assessments, with the nine township assessors
- First-level board
- DuPage County Board of Review
- Filing deadline
- 30 days after legal publication of the township's assessments (35 ILCS 200/16-55); each township's final filing date is posted on the Supervisor of Assessments' assessment status page, and appeals filed outside the window are rejected
- Commercial assessment level
- 33 1/3% of fair cash value (no classification outside Cook County), adjusted by township and county multipliers based on three-year sales ratio studies
- Value standard
- Fair cash value (35 ILCS 200/1-50)
- Valuation date
- January 1 of the assessment year
- Assessment cycle
- Quadrennial general reassessment (most recently 2023, next in 2027 on the four-year cycle), with township multipliers applied in the years between to hold assessments at 33 1/3% of market value
- Notices mailed
- Township assessment changes and multipliers are published in local newspapers in September and October, township by township; change notices are mailed by the Supervisor of Assessments (in 2026, for example, Downers Grove published October 1 and Milton October 9)
How DuPage County assesses commercial property
DuPage County runs the standard Illinois system outside Cook: property is assessed at 33 1/3% of fair cash value with no commercial classification, the nine township assessors set values, and the Supervisor of Assessments applies township and county multipliers so that each township's median level matches the statutory ratio. The last general reassessment was 2023 and the next falls in 2027, but changed assessments and multipliers are published every fall, township by township, so commercial owners face a new number every year.
The appeal window is short and fixed to publication. A complaint must reach the DuPage County Board of Review within 30 days after the township's assessments are legally published, and from 2026 the Board accepts appeals only through its SmartFile e-filing system. Evidence has to be uploaded with the complaint: three years of operating statements, current leases and a rent roll for income-producing property, and any appraisal within 10 days after the deadline. The Board accepts complaints from owners, taxpayers, or an Illinois attorney with proper authorization.
Hearings are short and usually by telephone, with a township deputy assessor defending the value. Written decisions typically arrive the following March, and the owner then has 30 days to go to the Property Tax Appeal Board, unless a stipulation and waiver of appeal was signed.
Major commercial submarkets
- Oak Brook and the I-88 East-West Tollway office corridor
- Naperville, Lisle and Downers Grove
- Itasca, Wood Dale and Elmhurst near O'Hare
- Addison and Bensenville industrial
- Carol Stream, West Chicago and the I-355 corridor
- Oakbrook Center and Yorktown Center retail
Uniformity authority
Ill. Const. 1970, art. IX, §4(a) (uniform taxation by valuation); 35 ILCS 200/9-145 (fair cash value at 33 1/3%); PTAB assessment equity rules, 86 Ill. Adm. Code 1910.65
Appeal statute
35 ILCS 200/16-55 (Board of Review complaints, counties under 3,000,000); 35 ILCS 200/16-160 (Property Tax Appeal Board)
After the board
Illinois Property Tax Appeal Board (PTAB) within 30 days of the date of the Board of Review's written notice of decision (35 ILCS 200/16-160), unless the owner signed a stipulation and waiver of appeal; alternatively a tax objection complaint in the Circuit Court of DuPage County after the taxes are paid under protest
Official forms ATALI ELECTRIC fills for DuPage County
| Form | Filed with | Purpose |
|---|---|---|
| Board of Review assessment complaint (Commercial/Industrial), filed in SmartFile | DuPage County Board of Review | The appeal itself, filed electronically within 30 days of the township's publication date, with all evidence uploaded at filing. |
| Attorney authorization for the parcel | DuPage County Board of Review | The Board accepts complaints from the owner, the taxpayer, or an Illinois licensed attorney with proper authorization; non-attorney agents are not among the listed filers. |
| Income-producing property package (three years of operating statements, current leases and rent roll) | DuPage County Board of Review | Required support for every income-producing property appeal under the Board's rules, uploaded with the complaint. |
| PTAB Commercial Appeal form | Illinois Property Tax Appeal Board | Second-level appeal filed within 30 days of the Board of Review's written decision; PTAB treats the deadline as jurisdictional. |
Filing system: DuPage County Board of Review SmartFile e-filing system (electronic filing is mandatory for all appeals from 2026)
Hearings and evidence
The three-member Board of Review schedules hearings by mailed notice, usually by telephone, in 15- to 20-minute slots that generally cannot be rescheduled. A township deputy assessor attends with the property record card and the assessor's evidence. The Board may offer a stipulated value; an owner who signs a stipulation and waiver of appeal gives up the PTAB route. Written decisions are mailed after the county's hearings are complete, typically the following March.
- 01All evidence must be submitted at the time of filing in SmartFile; the only grace period is for appraisal reports, accepted no more than 10 calendar days after the filing deadline.
- 02Income-producing property appeals should include three concurrent years of operating statements, current leases and rent rolls.
- 03Appraisals must be prepared by an Illinois State Licensed or Certified appraiser and state value as of January 1 of the year under appeal.
- 04The Board considers sales of the subject within twelve months of the assessment date as evidence of market value, so a recent purchase must be addressed head on.
- 05Mailed, paper and postmarked filings are not accepted; late complaints are rejected.
Income evidence
DuPage assessors set commercial values with income, sales and cost data, then the Supervisor of Assessments applies township and county multipliers so that the median level lands at 33 1/3% of market value. On appeal the Board expects a full income history (three years of operating statements, current leases and a rent roll) for any income-producing property, and it weighs that history against market rent, vacancy and cap rate evidence. For older suburban office in Oak Brook and along the I-88 corridor, where occupancy has lagged, a supportable stabilized vacancy and lease-up cost are usually what close the gap. Convert the indicated market value to assessed value at 33 1/3% and compare it to the published assessment, not to the equalized value on the tax bill.
Practitioner notes
- Watch the township calendar, not a county date: each of the nine townships publishes on its own date in the fall, and the 30-day window runs from that publication.
- Upload everything at filing. Unlike boards that set a later evidence date, DuPage only allows appraisal reports to trail the deadline, and by no more than 10 days.
- A multiplier year still opens the door: changed assessments and multipliers are published every year, and the Board hears complaints every year, not only in the 2023 and 2027 general reassessments.
- Read a stipulation carefully. Signing the Board's stipulation and waiver of appeal settles the year and forfeits PTAB review.
DuPage County appeal questions
Last verified October 2026 against the assessor, board and statute.
What is the commercial assessment level in DuPage County?
33 1/3% of fair cash value. DuPage has no classification system, so a $24 million industrial building should carry an assessed value of about $8 million before the state equalization factor.
How long do I have to file with the DuPage Board of Review?
30 days after legal publication of the township's assessments. Each township has its own publication date and final filing date, posted by the Supervisor of Assessments.
Can I mail a paper appeal?
No. From 2026 the Board of Review requires every appeal and all evidence to be filed electronically through SmartFile.
When can I go to PTAB?
Within 30 days of the Board of Review's written notice of decision, unless you signed a stipulation and waiver of appeal. Decisions are usually mailed the following March.
Nearby jurisdictions
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