We hope these FAQ give you a better idea of the work we do and how it relates to the overall property tax structure. We believe the public has the right to know what we do and how we do it. Please feel free to contact our office if you would like further clarification on any point or if you have any other questions.


How can I calculate estimated taxes?

Example for existing tax bills (does NOT apply to new construction)


      Assessed Value

    Exemptions (if applicable)

x    Tax Rate (i.e. 10.4709%)

=    Yearly Property Taxes

÷    2                                 

=    Per Installment Payment due in June & September

Which exemptions am I currently receiving?

You can find out your exemptions by calling the Winnebago County Supervisor of Assessments Office at (815) 319-4460 or click here to view them online.

Who paid the property taxes and when?

To view the current tax status click here to search a parcel by PIN, owner, or address.  NOTE: Limited to 5 searches per day. 

How may I combine adjacent properties to receive one bill?

You must complete a Real Estate Combination Request Form.  For additional questions about parcel combinations, please contact the Winnebago County Mapping Department at 815-319-4367. 

New Construction: Why did my builder send me a tax bill (i.e. an instant assessment)?

Both seller and buyer owe property taxes for the period of time they own the property. 35 ILCS 200/9‑180 explains that owners of property shall be liable, on a proportionate basis, for the increased taxes occasioned by the construction of new or added buildings, structures or other improvements on the property from the date when the improvement was substantially completed or initially used to December 31st of that year.  This allows for the owners and occupant of new construction to pay taxes for the value of their property for the part of the year that it was owned, completed, and occupied.  The Supervisor of Assessments Office can answer any further questions on this subject by calling (815) 319-4460.

What should I do if I don't think the assessed value given to my property is accurate?

Call your township assessor to talk over the matter with him or her.  Your assessor's phone number is displayed on the front of your tax bill, at the bottom of the box titled "Formula for Tax Calculation," on the left hand side of the bill.  A list of the names and phone numbers of the township assessors can be viewed HERE. Your assessor's phone number is also located in the pink box of your Assessment Change notice.

Who determines the tax rate?

The assessor has no control over the tax rate.  The County Clerk’s office is responsible for calculating real estate tax rates for all taxing districts within Winnebago County.  There more than 100 taxing districts, which receive property tax revenue.  Additionally, local citizens can influence spending by voicing their views to the proper officials.  The tax rate is dependent upon 1) school and local governmental levies [the amount of money a taxing body certifies to be raised from the property tax], 2) the statutory limits and 3) voter's response to referenda issues.

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How come building sketches are not available for commerical properties?

Our database cannot accommodate the size of most commercial, industrial, and multi-family buildings.  Therefore, sketches are on record in hardcopy and not electronic format.  If you need a sketch, please contact us and we will assist you.  We can fax or email you a sketch. 

What if the information I need is not listed on a commerical property?>

Call our office and ask for it.  Often times it will be in our database, but simply not listed on the web.

Which properties are classified as commercial?

Commercial properties include multi-family dwellings that are at least 4 units or more, and any commercial or industrial buildings.  Agricultural is listed under residential.

What is the Assessment Cycle?

  1. Township Assessor: January 1st of each year your property is assessed by the Township Assessor.
  2. Supervisor of Assessments: Mid to late summer, the Assessor completes his or her valuation and turns the assessment roll over to the Supervisor of Assessments. The Supervisor of Assessments applies an Equalization Factor on a Township basis to bring the level of assessments to the State required 33.33% (one-third) of market value.  
  3. Assessment Change Notices Mailed & Published: Late summer to early fall, written notice of the Assessor's changes are mailed to the property owners as well as publishing in the local newspapers a list of all parcels where values changed from the previous year.  NOTE: 2007 (and every four years before and after) is a General Assessment Year.  Every property owner during a General Assessment Year receives an Assessment Notice.  All other years, a property owner is noticed only if the Assessor made a change that effects the property’s value.  
  4. Filing a Complaint: Within 30 days of the above publication & notice, assessment complaints may be filed with the Board of Review.
  5. Board of Review:  Mid fall to early winter, hearings are held by the Board of Review to hear complaints filed.  The Board of Review also revises the assessment roll as necessary.
  6. State of Illinois Property Tax Appeal Board: After written notice of the Board of Review decision, the taxpayer may within 30 days file an appeal with the State of Illinois Property Tax Appeal Board.  
  7. County Clerk:  Late winter to early spring, the Board of Review turns the revised assessment roll over to the County Clerk, where tax rates are determined and the roll is certified. 
  8. County Treasurer: After certification, the County Clerk turns the assessment roll over to the County Treasurer.  Tax bills are prepared for mailing by the County Treasurer.  The bills are usually mailed in May and due in two equal payments in June and September.  Therefore, as an example, an assessment placed on your property as of January 1 this year, causes a tax bill to be issued in May of next year.

What is a "Property Record Card"?

Each habitable structure is listed as a separate record or card. For example, if a property contains two houses that property will have two cards.

How do I obtain a copy of my property record card?

You can call or visit the Office of the Assessor.  We can print, email, or fax you a copy. 

Why aren't market or assessed values shown on the website?

Value information is subject to change, either caused by changes in a property's description or by the action of the Board of Review. To avoid confusion we do not display it.  For the latest known assessment data, you can visit www.wingis.org.  When viewing the Property Details page, click Assessment Details.

Why is information for Commercial & Industrial properties not shown?

Commercial & industrial property is currently being re-listed.  When all of it is deemed accurate it will be shown.

Why aren't site areas shown on record data?

Our database does not allow for site area aerials.  You can visit www.wingis.org and view the site area by clicking the binoculars in your search results page.

What is the source of the "Owner and Legal Information"?

The Rockford Township Assessor's Office receives this information from Winnebago County. The ultimate sources are recorded documents such as deeds, plats, surveys and so on.

Where does the Year Built come from?

For structures built in the past 50 years or so the source is the building permit. Generally, the Year Built for older houses is an educated guess.

Why are there no dwellings with a Year Built date prior to 1900?

Our Database system does not have the capability to store years before 1900. Therefore "1900" means 1900 or before.

What are the different types of Attics?

NONE - No attic or an attic area without a permanent stairway
UNFINISHED - Unfinished area accessed by a permanent staircase
PART FINISHED - Like Unfinished, but having some finished, heated area
FULL FINISH - Fully finished and heated
FULL FIN WALL HGT - Fully finished and heated, with at least one dormer.

What is the difference between "Rec Room Area" and "Finished Basement Living Area"?

In both cases the amount of finish space must be sufficient to qualify as useful space that contributes to value and is shown in square feet. The difference between the two is that Finished Basement Living Area is found in basements that are partially or fully exposed.

Are prefabricated fireplaces listed as "Wood Burning Fireplaces"?


What is a "Part Masonry Wall"?

This classification is used when a building has some brick veneer, but not enough to qualify to list the Exterior Walls as Brick and Frame. Shown in square feet, it typically used for cases of brick trim, half wall brick fronts, etc.

What is meant by "Unfinished Area"?

This is that part of a building that is not habitable due to destruction (fire, storm damage, etc.), demolition or incomplete construction.

What is "Total Living Area" and "Above Grade Living Area"?

Total Living Area is shown in square feet and includes the building area, minus any Unfinished Area, plus any Basement Living Area. Above Grade Living Area is the same except that it does include any space below grade. In both instances the areas of structures such as garages and porches are NOT included.

How accurate are the measurements and areas on building sketches

Dimensions are rounded to the nearest foot. Therefore, areas may not be absolutely accurate. Use the dimensions and areas shown on this site with caution!

Why is the day not in the sale date?

We record only sale month and year.

What is meant by a sale type?

Three types of sales are possible: 1) land only, 2) improvements only and 3) land with improvements. NOTE: Vacant land will be listed as Land & Bldg if it contains any improvement that generates a value, no matter how small a value that may be.

Why doesn't the Sale Price (Amount) match that from another source such as a Multiple Listing Service?

The sale prices listed are NET amounts after any declared personal property is deducted from the total sale price. We do not keep track of the value of personal property claimed, if any.

What is meant by the "Validity" of a sale?

Internally, this is how we delineate sales that qualify as good, market sales from those that may not qualify as arms length transactions. 

What does "Delete" mean in the sale data?

This designator is applied to a sale if more than one property was sold or if the property was not exposed to the open market.

Where does the Building Permit information come from?

We receive notifications from the City of Rockford, City of Loves Park, and from Winnebago County.

Why do some of the Building Permit dates have "00" as the month?

We list the month and year in which each building permit is issued. If an inspection reveals that an improvement was added without a building permit it is designated by listing the month as "00".

How accurate is the Building Permit amounts?

This is the figure, often rounded, that the permit applicant estimated as the cost of the work being done. Our best advice is to use this figure with a good deal of caution. The Purpose column shows the work being done in summary form.

Why are some dimensions not shown on the record?

Every effort is made to draw the Sketch to scale. Small or crowded dimensions are not shown in the interest of legibility.

Where is the front of the building on the sketch?

It is always at the bottom, as if facing it from the street.

What is an "Attachment" or "Addition" on the record information?

For descriptive purposes each building has a main section, labeled as "A" in the attachments table. The main section (A) includes the total above grade living area plus, if applicable, finished attic space & finished basement living area.  Any attached structure(s) such as more living space, garage, porch, deck, etc. are additions and each has its own value. 

What sort of improvement is included in detached buildings and yard improvements?

Detached buildings such as sheds, garages and agricultural buildings.  In addition detached decks, patios and porches plus such things as swimming pools and tennis courts.  Driveways are listed, but not valued (the items with no size and a year built of 1900).

Other than driveways, what other types of improvements are not valued?

Sidewalks, fences, landscaping plus any improvement not permanently affixed to the land are not listed. 

What are the attributes considered when valuing my property?

Close to two dozen attributes are considered when valuing property.  Attributes include, but are not limited to, square footage, number of stories, type of construction, foundation type, heating type, plumbing fixtures, garage style, central air, finished space, stoops/decks/patios, porches, quality or grade of construction, masonry trim, fireplaces, cost factors, neighborhood or design factors, condition of property, and/or depreciation.  When considering your own comparables to support a complaint, you are best advised to consider the same attributes as well.

Why has my assessment changed?

Your township assessor may have revalued your property or, as required by law, an equalization factor was applied by the Winnebago County Supervisor of Assessments to adjust the level of assessments in each township to 33 1/3%.  For specific reasons, please contact our office at (815) 965-0300 for an explanation. 

What is fair market value?

Fair Market Value (FMV) is what an informed buyer would pay to a seller for a piece property on the open market.  Often times, due to assessments being compared on a mass appraisal basis, our FMV may be lower, higher, or right at the true FMV.  If you feel that your assessment in incorrect, please call our office at (815) 965-0300 to discuss your assessment. 

What is assessed value?

Assessed Value is considered to be 1/3 of the Fair Market Value.

Why can't my assessment be reduced to the sale price?

It can.  But only at the Board of Review level and only if it is an arm’s length sale.  The Office of the Assessor statutorily does not have the authority to reduce assessments based on sales price.  However, if the Office of the Assessor determines just cause, it can lower a condition, design or neighborhood factor.  If that does not satisfy the owner, it is best to file a complaint with the Board of Review. 

What is a township equalization factor & a county multiplier?

The Supervisor of Assessments or the Board of Review applies the Township Equalization Factor.  Each of the 14 townships in Winnebago County can have a different equalization factor.  Its purpose is to equalize all townships within a county to the same level of assessments.  The Illinois Department of Revenue applies the County Multiplier to equalize all counties in the state to the same level of assessments.  The level of assessments trying to be attained is 1/3 of fair market value at the township, county, and state levels. 

What is a valid sale?

A sale is considered valid when the transaction is an arm’s length transaction and conveyance is via a warranty deed.  This includes all parties being knowledgeable of the market, making informed decisions without undue influence, having the property exposed to the open market, and/or not involving a financial or governmental agency as the principal buyer or seller.  


A sale is considered invalid if it meets one or many of the following:  it involves a financial or government agency; multiple parcels are included in a sale price; when one parcel is being divided into multiple parcels; parties are related individuals or corporations; the sale is mandated by the court; when only a portion of the parcel or interest is transferred; when parcels are traded; if a deed other than a warranty deed is used to convey the parcel(s); or if the property was not exposed to the open market. 

How may I obtain my assessment history?

You may find your assessment history by calling our office or visiting WinGIS, (click Assessment Details, then Assessment History).

Is my home in a flood plain?

WinGIS provides current FEMA Flood Data to the public.  To view this data, search your parcel, click its PIN on the search results page, click Flood Zone, Voting District, Zoning and More located just under the Available Parcel Sales History, then click the Flood Zones link.  In bold red letters, it will read whether you are in or out of a FEMA flood zone.  For accuracy, you are advised to verify all data. 

Why are there two values on my property (land and building)?

Land is a supply that is naturally fixed and considered indestructible.  Therefore, its value generally does not decrease.  However, improvements or buildings can frequently change in value based on condition, design, and other attributes or events.

What is an assessment change notice?

An assessment change notice is a notice mailed by the Supervisor of Assessments office to notify an owner that the Assessor has changed the property’s value.  It is important to note that these notices are published and the period to file a complaint is 30 days from publication.  Please remember, your tax bills will be based on the assessed value on the notice. 

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