DuPage County homeowners should treat an assessment appeal as a valuation question, not a tax-bill complaint.
The county's assessment appeal process says property owners have an annual opportunity to appeal assessments to the DuPage County Board of Review. The filing period begins June 10 of the assessment year and ends September 10 or **30 days after the publication of the township assessment roll, whichever is later**.
That "whichever is later" language matters. DuPage is township-driven, so homeowners should check their township publication timing instead of assuming one universal date.
Call the township assessor first
DuPage County's process encourages property owners to call or visit the Township Assessor's office before filing. That is not busywork. The assessor can explain the property record, assessment logic, and whether a correction is possible before a formal appeal.
If the value still looks too high, the Board of Review appeal is where evidence comes in.
What evidence should look like
DuPage County says an appeal is an attempt to prove the assessed value overstates market value or is higher than similar properties. That means the best evidence usually falls into two lanes:
- Recent comparable sales if the argument is market value.
- Similar comparable assessments if the argument is assessment uniformity.
The county process specifically points homeowners toward three or more comparable properties. They should be similar to the subject property and, ideally, in the same neighborhood.
Watch the form details
DuPage appeal forms ask for the owner's view of fair market value and the proposed assessment. They also distinguish between value, uniformity, recent sale, appraisal, construction cost, and other grounds.
Do not rush that part. A thin appeal with weak comparables can waste the filing window. A focused appeal with clean evidence is easier for the Board to understand.
Censum county data snapshot
Censum's Illinois parcel database currently includes **336,932 DuPage County parcel rows**, including **336,199 rows with an assessed-value field**. The largest DuPage place-name buckets in the raw file include Naperville, Downers Grove, Wheaton, Lombard, Elmhurst, and Aurora.
That makes DuPage one of the stronger Illinois expansion counties for county-specific screening, comparable logic, and future confidence scoring.
Source links
- DuPage County assessment appeal process PDF
- DuPage County residential assessment appeal form
- Illinois Department of Revenue assessment appeal guidance
Censum note
Censum is building county-specific Illinois guides so homeowners can separate deadline, evidence, and pricing decisions before choosing whether to file themselves or hire help.