BMI Bornstein LLC’s Property Tax Blog

8 Common Property Tax Mistakes to Avoid

Mon, 10 Nov 2025 20:06:26 GMT

After years of consistently ranking among states with the highest property taxes, Illinois now has the highest property tax rate in the country. To make matters worse, many taxpayers commit errors—costing them thousands of dollars over the life of a property—when trying to navigate the property tax system alone.

Below are eight common property tax mistakes our firm sees most frequently when reviewing new client files, along with some practical tips to avoid these costly mistakes.

1. Missing Appeal Deadlines

Property tax appeal bodies have strict deadlines—typically 30 days from the notice date of assessment or a decision from a lower level of review. Missing these deadlines could mean forfeiting the right to challenge a property’s assessment for that year.

Pro Tip : Subscribe to assessor calendars or hire counsel who regularly monitors deadlines.

2. Submitting Insufficient Evidence

Appeal bodies need proof—not opinions. Simply disagreeing with a property’s assessment is not enough to persuade decisionmakers that reductions in assessed value are warranted.

Pro Tip : Gather and submit supporting evidence, such as recent comparable property sales, photographs, appraisals, or income/expense statements, to strengthen an appeal.

3. Confusing Taxes with Assessments

Arguing that a tax bill is too high, while failing to address the property’s valuation, typically results in dismissal or rejection of an appeal. Tax rates are set separately by local taxing districts, and appeals should primarily target inaccuracies in the assessed valuation itself. Consequently, any reductions in assessed value translate into reductions in the overall tax bill.

4. Overlooking Misclassifications and Data Errors

As of late, we have seen numerous examples of properties located in Cook County being misclassified, resulting in unexpected tax bill and mortgage payment increases. Common errors include phantom square footage, non-existent finished basements, and erroneous property classifications (e.g., commercial instead of residential).

5. Relying on Public Real Estate Websites

Public real estate websites like Zillow or Redfin can be helpful for general estimates and insights about a specific property but often provide inaccurate data and market values. Available county assessment records for similar properties and formal appraisal reports carry significantly more weight in a property tax appeal.

6. Not Escalating Appeals

Many property owners give up if their initial appeal is denied. However, Illinois offers three levels of appeal:

(1) County Assessors;

(2) County Boards of Reviews; and

(3) State Property Tax Appeal Board (PTAB) or Circuit Court.

Pro Tip : If an appeal fails at a lower level, or the desired result is not obtained, it should be escalated to the higher levels.

7. Neglecting Exemption Opportunities

Illinois law provides several exemptions, such the homeowner, senior, and disabled persons, that can provide substantial savings for eligible homeowners. Unfortunately, many homeowners miss out on these additional savings by failing to apply for or renew exemptions. Neglecting to apply for or renew these can cost hundreds or even thousands of dollars annually.

Pro Tip : If an exemption was missed on a prior bill, a Certificate of Error can be filed within a statutory period for a retroactive refund.

8. Attempting Complex Appeals Without Help

While straightforward residential appeals are certainly manageable independently, complex properties—such as commercial, industrial, or multi-family buildings—often require professional guidance. Hiring experienced legal counsel significantly enhances your likelihood of success.

Key Takeaways

How We Can Help

Our attorneys focus exclusively on Illinois property tax matters, and we have systems in place to provide clients with the following services:

Deadline monitoring in every county to prevent missing a filing window.
Building data-driven valuation cases using certified appraisals and assessor-grade comps.
Auditing exemptions and filing Certificates of Error for retroactive refunds.
Full-scope representation at all levels of review—Assessor, Board of Review, and PTAB/Circuit Court.

Questions about your 2025 assessment? Contact us for a complimentary review before the next deadline closes.

About the Firm

At BMI Bornstein LLC , we specialize in property tax law and offer expert services in property tax appeals across Illinois. Our experienced team can help you understand your property tax responsibilities and fight any unfair tax assessments. Contact us today to schedule a free consultation and learn how we can assist you with property tax issues in Illinois.

DISCLAIMER: This blog post is for informational purposes only and does not constitute legal advice. Consult an attorney for guidance on your specific situation.

Top 7 Reasons to Appeal Your Property Tax Assessment

Wed, 06 Aug 2025 23:52:26 GMT

Receiving a property tax assessment notice can feel overwhelming, especially when the numbers on the notice appear significantly higher than expected. Fortunately, Illinois property owners have the right to challenge inflated assessments. Below are the most common— and most successful —reasons our Illinois property tax team sees for challenging assessments and lowering tax bills.

1. Overvaluation: Assessed Value Above Fair Market Value

The assessed value of property should reflect what a property would sell for in a fair, arm’s-length sale on the open market on January 1 of the assessment year. However, many county assessors rely on mass-appraisal models, which sometimes yield absurd values that are much higher than the true fair market value of a property. If a property is assessed at a higher value than what it could realistically sell for, it is overvalued, and the owner should consider an appeal. Key evidence for establishing overvaluation can include the following:

recent sales data for the subject property;
comparative analyses of recent sales data for similar properties in the area; and
appraisal reports (preferably, from the same assessment year).

2. Lack of Uniformity with Similar Nearby Properties

Illinois law requires property taxes to be levied equitably and uniformly. If a property is assessed at a higher rate than similar properties nearby (less than a mile away), there might be grounds to appeal. Generally, the best evidence for this type of appeal is 3-5 neighboring properties with similar attributes (e.g., class, size, age) that all have lower assessments than the subject property.

3. Vacancy or Low Occupancy Rate

Commercial properties (including some multi-family properties) with prolonged vacancy or lower-than-average occupancy rates commonly have less income-producing potential, which can drastically reduce property value. Presenting evidence such as the following can go a long way to support requests for a reduced assessment:

rent rolls;
vacancy photos; and
marketing reports/brochures, detailing leasing efforts.

4. Errors in Income Approach/Calculation

Assessors often rely on an income approach to establish the value of income-producing properties. In these cases, any incorrect assumptions or erroneous calculations can result in inflated property values. Providing the data listed below is crucial for correcting any errors and demonstrating that a reduction is warranted:

current lease samples;
tax returns documents (from the previous 3 years, if available);
income/expense statements; and
market-supported cap-rate studies.

5. Physical Condition: Damage, Deterioration, or Obsolescence

If a property has suffered damage (e.g., fire, flood, tornado) or deterioration (e.g., structural issues, deferred maintenance, chronic roof leak), it will typically have a reduced market value. Appeals based on physical condition can be substantiated with the following evidence:

insurance claims;
contractor estimates;
engineering reports; and
photos of the damage or obsolescence;

6. Incorrect Property Characteristics

Assessors sometimes rely on outdated property data that contain errors—e.g., incorrect square footage, number of rooms, or property amenities—which can inflate property tax assessments. Reviewing the assessor’s records and correcting any inaccuracies through documented proof, such as blueprints, photographs, or building permits, can lead to successful corrections and tax savings.

7. Recent Change in Use or Zoning

Any changes in zoning or usage of a property can significantly impact its value. For example, if a property is reclassified from commercial to residential, or a warehouse is converted into self-storage, it may qualify for a different valuation model, resulting in a lower assessed value. Common evidence necessary for these types of appeals includes the following:

floor plans, surveys, appraisals, or other documentation, showing an accurate description, the square footage, and current usage of the property;
photos of the property’s interior/exterior; and
affidavits of use.

Why Work with a Property Tax Attorney in Illinois?

While many property owners can certainly appeal independently [1] , a professional property tax attorney can significantly enhance the chances of a successful appeal. At BMI Bornstein LLC , our attorneys are experts in property tax law . They handle hundreds of appeals every year and have the knowledge and experience to do the following for clients:

precisely analyze property assessment to identify errors and unfair assessments;
effectively gather and present compelling evidence;
navigate the complex appeals process and deadlines efficiently; and
advocate strongly for clients’ interests before the Boards of Review or Illinois Property Tax Appeal Board (PTAB).

Take Action Before Your Appeal Deadline

Remember, Illinois counties have strict deadlines for filing appeals, typically within 30 days from the assessment notice date or a decision from a lower level of review. Contact our experienced property tax attorneys today for a complimentary assessment review to ensure you pay only your fair share. Stop overpaying and start saving!

[1] In Cook County, the Board of Review requires that taxpayers, including, but not limited to, entities such as corporations, LLCs, and condominium associations, must be represented by an attorney.

DISCLAIMER: This blog post is for informational purposes only and does not constitute legal advice. Consult an attorney for guidance on your specific situation.

Understanding the Illinois Property Tax System: What Every Property Owner Should Know

Wed, 30 Jul 2025 11:20:20 GMT

Property taxes in Illinois can be complex and overwhelming, but understanding the system is essential for homeowners, business owners, and anyone involved in property ownership. Whether you are a first-time homebuyer, a seasoned investor, or just trying to understand how your tax bill is calculated, having a basic knowledge of the Illinois property tax system can help you make informed decisions and ensure you are only paying your fair share.

In this post, we break down the key components of the Illinois property tax system, including how properties are assessed, the tax rate process, some common exemptions available to taxpayers, and what you can do if you believe your property tax assessment is incorrect.

The Basics of Property Taxes in Illinois

In Illinois, property taxes are governed by a combination of state statutes and local ordinances, meaning that tax rates, exemptions, and assessments can vary by county and municipality. The state of Illinois does not impose a state property tax; instead, property taxes are generally levied by local government taxing districts to fund essential public services (e.g., schools, emergency services, and infrastructure projects) at the local level. The following section explains the process for calculating property taxes .

How Property Taxes are Calculated in Illinois

There are four main factors that go into calculating property tax bills in Illinois:

assessments;
equalization factor;
tax rate; and
exemptions.

I. Assessments

Illinois operates under a system where property tax calculations are based on the fair market value of a property. The fair market value (or fair cash value) is the amount for which a property would sell in a competitive and open market under normal conditions. Local county or township assessors generally determine the fair market value using one or more of the following approaches:

Sales Comparison Approach (Most Common)

The sales comparison approach is the most widely used method for determining fair market value, especially for residential properties. For this approach, the subject property is compared to recently sold, comparable properties (referred to as "comps") in the area. Key factors such as location, size, condition, age, and features of the property are considered. Adjustments are made based on differences between the comps and the subject property to estimate its market value.

Cost Approach

The cost approach is typically used for newer properties or unique properties that do not have many comparable sales. This method involves estimating the cost to replace the property (or improve it) with a similar one, subtracting depreciation for any loss of value due to age or condition. The land value is calculated separately and added to the depreciated value of the improvements (the buildings and other structures).

Income Approach (for Income-Producing Properties)

The income approach is often used for commercial, industrial, or multi-unit rental properties that generate income. It involves estimating the property’s potential income (such as rents from tenants) and applying a capitalization rate (“cap rate”) to estimate the property’s present value.

Once the fair market value is established, local assessors determine the assessed value of a property, which is a percentage of the fair market value. Illinois law requires that the assessment level on most non-farmland property equal one-third (33.33%) of a property’s fair cash value, regardless of whether the property is residential or commercial/industrial.

There are some exceptions to this rule, however, such as different levels for farmland assessments and in counties with a population of more than 200,000 that classify property for assessment purposes. Regarding the latter exception, Cook County is the only county in Illinois that has adopted such a system. In Cook, residential properties (including apartment buildings and vacant parcels) are assessed at 10% of fair market value, while commercial and industrial properties are assessed at 25% of fair market value.

II. Equalization Factor

The equalization factor (or multiplier) adjusts the assessed value of properties to ensure fairness and consistency across Illinois. Its purpose is to equalize assessments, ensuring properties are assessed at approximately one-third of their market value, as required by law. The Illinois Department of Revenue calculates the equalization factor based on average assessments for each county.

If a county’s assessments are too high or too low, the equalization factor ensures they align with the state’s standard.
For example, if a county assesses properties at 30% of market value, the equalization factor may be greater than 1 to bring it to the required 33.33%.

III. Tax Rate

Once the property’s assessed value is determined, local government taxing districts (e.g., counties, municipalities, school districts) apply a tax rate (or levy) to calculate the property tax bill. The tax rate is typically expressed as a percentage, and the more taxing districts a property falls under, the higher the overall tax rate will be.

IV. Exemptions

In Illinois, there are several property tax exemptions that can help reduce the amount of taxes owed. As mentioned above, the amount an exemption reduces your tax bill can vary based on county or municipality. Here are a few of the most common exemptions:

General Homestead Exemption : This exemption is available to homeowners who occupy their property as their primary residence. It reduces the equalized assessed value of the home by up to $10,000, depending on location.

Homestead Exemption for Persons with Disabilities : Persons with a verifiable disability may qualify for an additional exemption, further reducing the equalized assessed value of their property.

Senior Citizens Homestead Exemption : Seniors who are 65 or older may qualify for an additional exemption that can reduce the equalized assessed value of their property by up to $8,000.

Senior Citizens Assessment Freeze Exemption : This exemption helps low-income seniors by freezing the equalized assessed value of their home at a certain amount, preventing increases in property taxes due to rising property values.

Calculating the Property Tax Bill

Now, putting all the parts mentioned above together, a tax bill calculation for a residential property in Cook County would look like this:

Here is another example for a residential property tax bill calculation in DuPage County:

What to do if Your Property Tax Assessment is Incorrect

It is common for property owners to notice discrepancies in their tax assessments or feel their tax rate is too high. If you believe your property tax bill is incorrect or unjust, you have several options to fight this:

Review Your Assessment : Check the assessment notices sent by your local assessor. If your property’s value is higher than the actual fair market value, you may may be able to reach out directly to your local assessor and convince them to reduce your assessment. However, this informal approach has a relatively low success rate; in many cases, you will need to file a formal appeal (or complaint) either with the assessor’s office or local board of review.

File an Appeal : If you disagree with the assessment, you can file a formal appeal with the assessor’s office or local board of review. If you are dissatisfied with the outcome of your initial appeal, you can appeal to the Illinois Property Tax Appeal Board (PTAB) or, in some cases, the courts.

Hire a Property Tax Attorney : A property tax lawyer can help gather the necessary documents, such as recent sales data or property appraisals, to support your appeal. They can also represent you in hearings at all levels, ensuring that your case is handled effectively.

Conclusion

Understanding the Illinois property tax system is essential for any property owner in the state. With this knowledge, you can ensure that your taxes are fair, take advantage of available exemptions, and take action if you believe your assessment is inaccurate. If you are unsure about any aspect of the property tax process or feel that your assessment is too high, a property tax law firm can provide valuable guidance and help you navigate the complex world of property taxes.

As property owners, staying informed about property tax laws can ultimately save you money and ensure you are only paying your fair share—no more, no less.

About the Firm

DISCLAIMER: This blog post is for informational purposes only and does not constitute legal advice. Consult an attorney for guidance on your specific situation.