Travis Bunn

Founder, AppealDesk · Published March 11, 2026 · Updated August 25, 2026

Illustrative Example: A $2,831/Year Overassessment in Woodstock, IL (McHenry County)

Updated August 2026 · 9 min read

The Numbers at a Glance

The Situation

Woodstock sits about 50 miles northwest of Chicago in McHenry County, one of the collar counties where property taxes are among the highest in the nation. Illinois homeowners routinely face effective tax rates above 2%, and McHenry County is no exception at 2.37%.

Picture a homeowner in a standard Woodstock neighborhood receiving an assessment notice showing a value of $320,046. The number seems high, and recent sales nearby tell a very different story.

The question is simple: does the county's number match what comparable homes are actually selling for?

In this scenario: not even close.

Building the Evidence: 5 Comparable Sales

The foundation of any successful property tax appeal is comparable sales data. Not Zillow estimates. Not gut feelings. Actual closed transactions of similar properties nearby.

For this Woodstock property, 5 comparable sales were identified -- all within McHenry County, all sold within the past 12 months, all with similar characteristics:

• Similar square footage (within 20% of the subject property)
• Same general area and school district
• Comparable age and construction type
• Arms-length transactions (no foreclosures, estate sales, or family transfers)

The median value of these comparable sales came in at $200,560 -- a full $119,486 below the county's assessed value.

This was not a marginal difference. The county was valuing the home at 37.3% more than what the actual market was paying for similar properties.

Why McHenry County Assessments Run High

Illinois uses a triennial assessment cycle in most counties, meaning values can lag or overshoot the market depending on when the last reassessment occurred. Several factors contribute to overassessment in McHenry County:

• Mass appraisal methods -- the county uses computer models to value thousands of properties at once, which misses individual property conditions
• Lagging data -- assessments may be based on sales from 12-24 months prior, which in a cooling market means the county is using peak prices
• High tax rate dependency -- at 2.37%, even small overassessments translate into significant tax dollars, creating less incentive for the county to lower values
• Low appeal rates -- most homeowners never challenge their assessment, so errors go uncorrected year after year

The Appeal Process in McHenry County

Illinois has a structured appeal process that flows through the Board of Review:

1. File with the McHenry County Board of Review within 30 days of the assessment publication date
2. Submit evidence including comparable sales, property details, and your proposed value
3. Board reviews the case and may schedule a hearing (many cases are decided on evidence alone)
4. Receive a decision -- if denied, you can escalate to the Illinois Property Tax Appeal Board (PTAB)

The critical element is the evidence packet. A Board of Review member reviewing dozens of appeals per day needs to see, at a glance: your current assessment, the comparable sales that prove it is too high, and the specific value you are requesting.

What $2,831/Year Actually Means

Property tax savings compound because a corrected assessment typically holds for the remainder of the assessment cycle. Here is what $2,831 in annual savings looks like over time:

• 1 year: $2,831 saved
• 3 years: $8,493 saved
• 5 years: $14,155 saved
• 10 years: $28,310 saved

For a $49 evidence packet, that is a 57x return on investment in the first year alone. Even if the Board of Review grants only a partial reduction, the savings still dwarf the cost of building the case.

Lessons for McHenry County Homeowners

This case illustrates several patterns common across McHenry County and the broader Chicago suburbs:

• Overassessments are not rare. A 37% gap between assessed value and market value is larger than most, but double-digit overassessments are common in Illinois collar counties.
• High tax rates amplify the impact. At 2.37%, every $10,000 of overassessment costs $237 per year. That adds up fast.
• The evidence exists. Comparable sales data is available for every neighborhood. The question is whether homeowners take the time to compile and present it.
• Most people never check. The majority of homeowners pay whatever the county says without comparing to actual market data. That is money left on the table.

The Bottom Line

In this illustrative scenario, a Woodstock homeowner is paying taxes on a $320,046 assessment when comparable sales show a market value of $200,560. The 37.3% overassessment translates to $2,831 in excess taxes every year -- $28,310 over a decade.

The evidence is there for gaps like this. It just needs to be compiled, organized, and presented to the Board of Review in the format they expect.