Ever looked at your Oak Brook tax bill and wondered why that number doesn’t match a recent appraisal or your list price? You are not alone. Appraisals and assessments sound similar, yet they are created for very different reasons and can produce very different values. In this guide, you will learn what each value means, how DuPage County sets them, how appeals work, and what to do next whether you are buying, selling, or simply managing your taxes. Let’s dive in.
Appraisal vs. assessment basics
An appraisal and an assessment both place a value on your home, but they serve different purposes.
What an appraisal is
An appraisal is a licensed appraiser’s professional opinion of your home’s market value on a specific date. It is property specific and follows USPAP standards. Lenders use appraisals in purchases and refinances, and you might order one for pricing, estate planning, or during negotiation.
What an assessment is
An assessment is the value assigned by the local assessor to determine property taxes. In Illinois, assessments are produced using mass appraisal methods and state rules. The value you see on county records is often the Equalized Assessed Value, or EAV, used to calculate your tax bill.
How DuPage assessments are set
In DuPage County, assessments are built using mass appraisal. The Assessor’s Office studies market activity and applies models across many parcels at once. Residential property has historically been assessed at 33.33 percent of market value to produce an assessed value, but you should confirm current ratios and equalization factors with DuPage County because rules can change.
Here is the general flow to a tax bill:
- Estimate market value through mass appraisal.
- Apply the statutory assessment ratio to get assessed value.
- Apply any required equalization factor to reach EAV.
- Subtract eligible exemptions to get taxable EAV.
- Apply the combined tax rates from all taxing bodies to compute the tax due.
Remember, the assessed figure used for taxes is not the same as the market value a buyer or lender will use.
How appraisals are done
Appraisers analyze recent comparable sales, inspect the property, and consider size, condition, amenities, and location trends. For most homes, the sales comparison approach is primary. The cost approach and the income approach may be used where appropriate, such as for new construction or rental property.
Why numbers often differ
- Valuation date. Assessments can reflect a prior cycle. Appraisals reflect a specific effective date that is often more current.
- Scope and detail. Appraisals are individual and property specific. Assessments apply models to many homes and may smooth out unique features.
- Purpose and rules. Assessors follow tax law and mass appraisal standards. Appraisers follow USPAP and lender requirements.
- Exemptions and equalization. Assessments incorporate exemptions and equalization. Appraisals do not.
Oak Brook process and timelines
Find your parcel data
Use the DuPage County property search or GIS parcel viewer to look up your address or PIN. You can review your assessed value and EAV, exemptions on file, sales history, and tax bills. The Treasurer’s Office handles billing and payment schedules.
Appraisals in a transaction
If you are buying with a loan, your lender will order an appraisal after you go under contract. Sellers and buyers sometimes order a private appraisal to help set price or to support negotiation. If an appraisal comes in lower than the contract price, the parties may renegotiate, supply additional market evidence, or the buyer can bring extra cash to close the gap.
Appeal your assessment
Start with an informal review by contacting the DuPage County Assessor’s Office to confirm property data such as square footage or exemptions. If you still disagree, file a formal appeal with the DuPage County Board of Review during the set filing window. Strong evidence includes recent independent appraisals, comparable sales, photos that show condition issues, and documents correcting property characteristics. If you remain dissatisfied after the Board of Review, you can seek further review with the Illinois Property Tax Appeal Board or in circuit court. Always check current county sites for this year’s deadlines and forms.
Exemptions and relief programs
Common exemptions that reduce taxable EAV include the homeowner’s (homestead) exemption, senior exemptions and senior freeze programs, disabled person exemptions, and disabled veteran or veteran exemptions. Most require an application through the Assessor’s Office and may need renewal or proof of eligibility.
What this means for you
For buyers
- Do not use the assessed value as a proxy for market value. Rely on current comparable sales and, if needed, a private appraisal.
- Review the seller’s recent tax bills and the parcel’s assessed value and EAV to estimate future taxes. Taxing districts can differ across Oak Brook neighborhoods.
For sellers
- Consider a pre-listing appraisal or a thorough market analysis to set a defensible price and prepare for lender scrutiny.
- Share known assessment and exemption details with prospective buyers. A high assessed value does not always equal a high market value, but it can affect tax expectations.
For current homeowners
- Check your parcel each year to confirm recorded data and exemptions.
- If comparable sales suggest your EAV is too high, gather evidence and request an informal review or file a Board of Review appeal during the window.
- Consider ordering an appraisal before an appeal, before listing, or before refinancing.
Quick number example
Suppose your market value is appraised at $600,000. If the statutory residential assessment ratio were 33.33 percent, the assessed value would be about $200,000. If the combined local tax rate were 2.5 percent, the annual tax would be 2.5 percent of $200,000, or $5,000. Exemptions would reduce the taxable amount and lower the bill. Always verify current ratios and rates with DuPage County.
Next steps in Oak Brook
- Look up your parcel to confirm assessed value, EAV, and exemptions.
- If something looks off, contact the Assessor’s Office for an informal data review.
- If you plan to buy or sell, request a market analysis and consider a private appraisal to firm up strategy.
- For significant appeal decisions, consult a licensed appraiser or a property tax attorney.
Work with a local advisor
Pricing and tax planning go hand in hand. You can position your sale or purchase with a clear view of market value, expected lender requirements, and the tax picture that buyers will weigh. If you are selling, targeted improvements and thoughtful presentation can raise your appraised market value and improve buyer confidence, while accurate assessment data helps avoid surprises.
Ready to align your valuation, listing plan, and tax strategy? Unknown Company. Let’s connect — start your renovation ROI plan.
FAQs
What is the difference between an appraisal and an assessment in DuPage County?
- An appraisal is a licensed appraiser’s opinion of market value for a specific date, while an assessment is the Assessor’s value used to calculate property taxes.
How is Equalized Assessed Value calculated for Oak Brook taxes?
- The Assessor estimates market value using mass appraisal, applies the statutory assessment ratio, then applies any required equalization to reach EAV, subtracts exemptions, and multiplies by local tax rates.
Do renovations increase my property taxes in Oak Brook?
- Improvements can impact assessed value because assessments reflect property characteristics; any change may alter EAV and, in turn, taxes, subject to exemptions and local rules.
Do I need an independent appraisal to appeal my assessment?
- You do not need one, but a recent independent appraisal can be strong evidence alongside comparable sales, photos, and corrections to property data.
Why are my Oak Brook taxes different from a similar nearby home?
- Differences can come from valuation dates, property characteristics, exemptions, equalization, and the specific taxing districts that apply to each parcel.
