Winnebago County gives a property owner 30 calendar days after the assessment list is published to file a complaint with the Board of Review. For 2026, the county's Board of Review page set that deadline at September 4 for Cherry Valley, Durand, Laona, Owen and Rockford townships, and September 5 for Burritt, Harlem, Harrison, Pecatonica, Rockton, Roscoe, Seward, Shirland and Winnebago townships. A complaint that arrives late is returned with no decision. This guide follows the whole path in the order an owner meets it: the township assessor, then the Board of Review, then the Illinois Property Tax Appeal Board.

If you are looking at homes for sale in Winnebago County, the assessment is one number on the parcel that you can question, and the county has a written process for doing it. Gambino Realtors has been in business in Rockford since 1923. This guide is a plain reading of the county's 2026 Board of Review rules and the state's own pages, and it is not legal or tax advice. The Board of Review office confirms what applies to your parcel. It can be reached at (815) 319-4463.

The Ladder: Assessor, Board of Review, State Board, Court

The Winnebago County Board of Review page describes the system as multi-level. The levels are the township assessor, the county Board of Review, the Illinois Property Tax Appeal Board, and finally court for an owner who is still not satisfied after those administrative steps. Each level has its own deadline and its own paperwork.

The first rung is informal. The county says the township assessor should be the first person an owner contacts. It gives a reason: an assessor who still has the assessment books for a given year can correct any assessment. Calling an erroneous assessment to the assessor's attention early in the year may result in a correction without using the formal appeal process. The Board of Review's own rules say the same thing from the other side. They say that many times the reason for an assessment can be made clear, or an error on the property record card corrected, which eliminates the need for a complaint.

Here is the catch, and the rules say it twice. By state law, the time period for filing a complaint is not extended while you talk with the assessor. A phone call with the assessor does not pause the 30 days. An owner who is still negotiating on day 29 has not filed anything. The sensible reading is that the assessor conversation and the filing clock run side by side, so the call should happen early and the form should be ready before the deadline.

The second rung is the formal complaint to the county Board of Review. That is the subject of the next section. The third rung is the Property Tax Appeal Board, a state body, which hears appeals from Board of Review decisions. The fourth rung is court. The statute that creates the state board says a taxpayer unhappy with the Board of Review "need not appeal the decision to the Property Tax Appeal Board before seeking relief in the courts." So court is not strictly behind the state board. It is a separate road.

Two other facts set the stage. First, the county's FAQ explains that a Notice of Real Estate Assessment is mailed when the township assessor changes the assessed value of a property. The notice is not a tax bill and does not state the amount of tax. Second, the same FAQ says 2023 and every fourth year after is a general assessment year. In those years every property is viewed and every taxpayer receives a notice, whether or not the assessment changed. In the years between, notices and publication are required only for parcels the assessor changed.

Filing With the Board of Review: Dates, Form, Copies and Standing

The statute and the county agree on the clock. A complaint to affect the assessment for the current year must be filed on or before 30 calendar days after the date of publication of the assessment list. The county page says assessments are generally published at the end of July and tells owners to check back mid-July each year for exact dates.

The 2026 schedule on the county page shows how the dates stack. The assessments went online July 31 at 5:00 PM for every township. Assessment notices were mailed August 3. Publication was August 5 for the first group of townships and August 6 for the second. The complaint filing deadline was September 4 and September 5. The deadline for additional evidence on a request to reduce the assessment by less than 100,000 dollars was September 29 and September 30. For a request of 100,000 dollars or more, it was October 14 and October 15. Those dates are for 2026.

The form itself is not optional. Under the 2026 rules, every complaint must be in writing on the Winnebago County 2026 Real Estate Assessment Complaint Form. It is available on the Board of Review page or at the office. The board will not send forms by overnight express or fax.

A few mechanics decide whether a complaint is even considered:

• A separate form is needed for each separately assessed parcel. A condominium board of managers files all of its unit complaints together, with a list of the parcel numbers.
• The owner files the original and one copy of the form, and the original and one copy of all written evidence. The rules also suggest keeping a complete copy.
• The form must be signed by the owner or someone with standing.
• Mail is treated as filed on its postmark date. A different delivery service counts as filed on the date on the shipper's tracking label. The rules say fax and email complaints will not be accepted.

The rules also set out who may file. An owner can file on their own property. A trustee can file for a trust. An estate representative can file for a recently deceased owner, with a death certificate or letter. Either party to an agreement for deed can file, with a copy of that agreement.

One rule matters to anyone who is buying. A person who has agreed to purchase a property can file a complaint on it if the scheduled closing is within 25 days after the filing deadline. The filing must include the entire purchase contract. That rule is narrow. A buyer who closes later than that window does not get standing through a contract.

What if the form is incomplete? The Board does not simply discard it. If a complaint is missing the property identification, the signature or the required copies, the board sends an acknowledgment that says which rules were not met. The owner then has 10 business days to bring it into compliance. If that is done, the complaint is processed like any other. If it is not, the board dismisses it. That grace period is for defects in the paperwork. It does not rescue a complaint that missed the 30 days.

What You Can Argue, and What Evidence the Board Weighs

The rules name three legitimate bases for a complaint. The first is overvaluation. The second is equity of assessment. The third is a discrepancy in physical data. Two things are named as not being a basis: the amount of taxes paid, and a change in the tax rates. The board also states that it has no authority over any valuation for a year before the current year, so the percentage jump from last year's assessment is not a valid basis by itself. The complaint has to say what is wrong with this year's number.

The county FAQ lists the reasons a bill can rise: new construction added to the assessment, a revaluation by the township assessor, an equalization factor, farmland revaluation, an exemption being removed, or a higher tax rate. Only some of those are assessment questions. The tax rate is set by the County Clerk, and the FAQ says plainly that the assessor has no control over it. A complaint about the rate is not a complaint the Board of Review can fix. The state board says the same about itself, that it has no jurisdiction over the amount of a tax bill or the tax rate. If your bill rose because an exemption fell off, the Winnebago County homestead exemptions guide is the place to start, and the guide to how a Rockford property tax bill is built shows where the rate lines come from.

Take overvaluation first. The rules define it as the equalized assessed value exceeding the property's fair cash value. Fair cash value is the amount for which a property can be sold in the due course of business and trade, not under duress, between a willing buyer and a willing seller. The county notes that the term is used interchangeably with market value. Assessments are made as of January 1 of the assessment year, and the rules say assessments reflect one-third of fair cash value. The burden of proof sits with the owner, who must show the value of the property by a preponderance of the evidence.

Because the assessment is one-third of value, the thresholds in the rules are in assessed dollars, not market dollars. That is a demonstration of the one-third rule, nothing more. It is not a prediction for any parcel.

For comparable sales, the Board looks at the best three submitted by the owner and the best three submitted by the township assessor. The rules want sales that are arm's-length market transactions, near the subject or in the same neighborhood, and similar in size, construction, quality, age, style and condition. Sales generally must have occurred after January 1, 2023 and before April 1, 2026 to count for the 2026 assessment. A sale of the subject property itself is not held to that date window. If all else is equal, sales closer to January 1, 2026 are considered more credible.

What does evidence look like on paper? The rules give examples: a complete signed closing statement for the purchase of the subject, with those closest to January 1, 2026 weighted heaviest, a complete appraisal, comparable sales data including MLS listings entered on the Comparable-Property Grid Sheet, a statement of construction cost, a description of physical characteristics if it differs from the assessor's, and recent photographs. The rules also say statistics about national, state, regional or city-wide values are considered less significant than information from the neighborhood.

An appraisal carries its own conditions. It must be certified in writing by the person who prepared it, follow the Uniform Standards of Professional Appraisal Practice, be signed, and be presented in full with every exhibit. The appraiser who prepared it is required to attend the hearing. An appraisal with a January 1, 2026 valuation date is preferred, and the rules say the farther the valuation date is from January 1, the less consideration it receives. An appraisal done with an interior inspection gets more weight than one without.

Equity is a different argument. The rules define an inequitable assessment as one that values the property at a higher level of assessment, relative to fair cash value, than similar properties. The burden is heavier here: clear and convincing evidence. The rules prefer the five closest matches, and the Board examines the first ten equity comparables from each side. The comparables should be in the same market area or subdivision and similar in size, construction, quality, age, style and condition.

The third basis is physical data. This one is about a fact on the record, not a value: the property record card says something that is not true of the house or lot, and the assessor relied on it. The rules require a statement highlighting the incorrect data and competent written evidence of the correct data, with a plat of survey, a photograph or construction documents given as examples. A mistake in a record is not the same as a disagreement over value, and the evidence is different too.

One more rule sits in this section because it can end an argument before it starts. If the township assessor, or a taxing body that has intervened, asks in writing by certified and regular mail to inspect the property, and the owner does not allow access or respond within 21 days, the Board will not accept evidence offered to refute the assessor's evidence on the property's description, physical characteristics or condition.

From Filing to Hearing to the State Board

What happens next depends on the size of the reduction requested, measured in assessed value. For a request of less than 33,333 dollars, the Board does a preliminary review using the written evidence from the owner and the assessor. It then sends a notice of its preliminary determination to the owner and the assessor. The owner may request a hearing within 10 business days after the date of the letter. If no hearing is requested, the value on the notice becomes the Board's assessment and the case is closed. No appearance is required.

For a request of 33,333 dollars or more, there is no preliminary review. A hearing is set automatically, and the owner or the owner's attorney has to attend. Hearings take place at the County Administration Building at 404 Elm Street, Room 301 or 303, between 8:00 am and 5:00 pm. Virtual hearings are available on request. Notice of the date comes by U.S. Mail. Hearings are scheduled in at least 15-minute blocks for requests under 100,000 dollars and at least 30-minute blocks at 100,000 dollars or more, and the presentation, the assessor's response and the Board's questions all have to fit.

The hearing has a set order. The owner presents oral testimony limited to the written evidence filed on time and to the subject property, and answers the Board's questions. The township assessor may cross-examine the owner, and the owner may cross-examine the assessor. Each side gives closing remarks. Exhibits such as charts, maps or photographs that refer to timely evidence have to be submitted five business days before the hearing. Only the owner or an Illinois attorney represents the owner. Accountants, tax consultants and appraisers can be expert witnesses but cannot conduct questioning or introduce evidence.

Hearings can be rescheduled once. An owner who does not appear receives a "Failed to Appear" notice and the case is closed. The state statute adds a second consequence: if an appeal is dismissed for failure to appear at the Board of Review hearing, the state board has no jurisdiction to hear a later appeal on that complaint. That applies when written notice of the hearing was given at least 30 days before it.

The owner can also read the assessor's side. For complaints of 33,333 dollars or more, or where a hearing was requested, the assessor's written evidence is posted through the county's Parcel Information Search under the parcel number, through a link on the parcel record labeled for the evidence. The rules FAQ puts its availability at no earlier than approximately two to four weeks after the filing deadline.

Deliberations are open to the public. A motion on the correct assessment needs the affirmative votes of at least two full Board members, and the final decision is in writing. The board's FAQ says that, in the ordinary case, a final decision letter is mailed within a week of the deliberations. The Board "corrects the assessment as appears to be just," in the words of the statute, and the same statute says no assessment can be increased until the affected person has been notified and given a chance to be heard. A decision changes the value for the current assessment year only. The Board cannot retroactively change earlier years' values.

If you disagree with the decision, the next step is the Property Tax Appeal Board. The statute gives 30 days after the date of written notice of the Board of Review's decision. The county page says the PTAB forms are available in the Supervisor of Assessments and Board of Review offices, and that PTAB hearings are generally held in Springfield. The state board's own filing page tells owners to check the date of the written decision first, because the appeal must be filed within 30 days. It also says a separate petition is needed for each year being appealed, and that faxed or emailed appeals are not accepted.

The state board's jurisdiction is narrow. It says it is limited to deciding the correct assessment of a property on equity and the weight of the evidence. It cannot review a tax bill or a tax rate, and it cannot exempt property. For a residential appeal seeking a change of less than 100,000 dollars in assessed value, the filing page says an owner can use comparable properties or an appraisal. A comparable-sales appeal needs at least three recent sales in the grid, and so does an equity appeal. The owner can ask for a decision on the evidence, which the page says may be faster, or an in-person hearing.

Does an appeal delay the tax bill? The statute says no. The extension of taxes on an assessment under appeal is not delayed by any proceeding before the state board. If the assessment is lowered, the taxes extended on the unauthorized part are abated, or refunded with interest if already paid. For a residence the owner occupies, a reduced assessment from the state board stays in effect, subject to equalization, for the remainder of the general assessment period. The exceptions are a later arm's-length sale that sets a different fair cash value, or a decision that is reversed or modified on review. If a bill comes due while an appeal is open, the delinquency rules in the guide to the Winnebago County tax sale still apply.

One related remedy sits outside the complaint window. A certificate of error requires evidence of an error in fact. The rules say requests for the 2025 tax year may be filed with the Clerk of the Board until the day of the tax sale for 2025 taxes. Condominium owners should also read the guide to condo and townhouse property taxes in Winnebago County, because a board of managers can file for all units, and an individual owner who files on time is treated as opted out of the association's filing.

Bottom Line

Winnebago County's assessment appeal process rewards the owner who moves early and files complete paper. Call the township assessor as soon as the notice arrives, because the 30 days do not wait for that call. Decide whether your case is overvaluation, equity or a wrong fact on the record, because each has a different burden and different evidence. Put the original and one copy of the form and every exhibit in the mail before the deadline, with a legible postmark. If the Board of Review decision is not what you hoped, the state board's 30-day window starts from the date on the written notice.

Taxes are not what the Board decides. It decides the assessment. A rate, a levy or a missing exemption belongs to a different office. Anyone comparing homes for sale in Winnebago County can use this guide to see what the number on a parcel means and how it can be challenged. For the dates that apply to your township this year, check the county's Board of Review page, and call (815) 319-4463 for anything the page does not say.

Those are the rules in order. Here are the questions that come up when an owner first holds the complaint form.

Frequently Asked Questions