A comparable property, often called a “comp,” is a property that is similar to yours and used to compare property values during a Cook County property tax appeal.

Comparable properties help show whether your property’s assessed value is higher than similar properties nearby.

If similar properties are assessed at a lower value, it may support your argument that your property is overassessed.

Why Comparable Properties Matter in a Tax Appeal

Cook County uses property comparisons to help determine whether an assessment is fair.

During an appeal, comparable properties can help demonstrate that:

• Your property is assessed higher than similar homes or buildings

• Your assessment does not reflect the local market

• Other similar properties in your area are taxed less

This evidence can strengthen your appeal and increase the chances of receiving a reduction.

What Makes a Property a Good Comparable?

A comparable property should be very similar to your property in several key ways.

1. Location

The property should be located in the same neighborhood or township.

Properties close to yours provide the most accurate comparison.

2. Property Type

The property should be the same type as yours.

Examples include:

• Single-family home compared to another single-family home

• A condominium compared to another condominium

• An office building compared to another office building

3. Size and Features

Comparable properties should have similar characteristics, such as:

• Square footage

• Lot size

• Number of bedrooms and bathrooms (for residential)

• Building age and condition

• Construction quality

4. Recent Sales or Assessments

In many appeals, comparable properties include:

• Recently sold properties

• Properties with lower assessed values

These comparisons help demonstrate market value differences.

Comparable Properties for Commercial Property Appeals

Commercial property appeals often rely on comparables such as:

• Similar office buildings

• Retail properties with comparable size and location

• Industrial properties in the same market area

Commercial appeals may also consider:

• Rental income

• Operating expenses

• Vacancy rates

Because commercial properties are more complex, selecting accurate comparables is especially important.

How Many Comparable Properties Should Be Used?

Many appeals include three to five comparable properties.

Using multiple comparables helps show a consistent pattern that your property may be assessed too high.

Key Takeaways

• A comparable property is a property similar to yours used to compare assessments.

• Comparables help show whether your property is overassessed.

• Good comparables share similar location, size, and property type.

• Both homeowners and commercial property owners can use comparables in an appeal.

• Strong comparable evidence can increase the chances of a successful Cook County property tax appeal.

Understanding comparable properties is one of the most important steps when preparing evidence to challenge your Cook County property assessment.