Property Search

When you’re trying to understand a tax bill, prepare to buy or sell a home, or get ready for an appeal, the first thing most people search for online is some version of “Cook County IL Property Search.” This guide walks you through how to actually use the official Cook County Assessor’s online systems to look up property information, see how your home was valued, compare it to similar properties, and figure out what to do next if something doesn’t look right. Everything here is based on official Cook County Assessor resources and is written for everyday property owners, buyers, and renters who just want clear, practical steps.

Get Oriented: How the Cook County Property Search System Fits Together

Before you start typing an address into a search box, it helps to know what you’re actually looking at and why it matters.

Cook County property records are maintained by the Cook County Assessor’s Office. For each parcel of real estate, the Assessor’s Office tracks:

An estimated market value (what the office believes the property is worth in the current real estate market)

An assessed value (the number used to help calculate your property taxes)

Basic property characteristics (building type, square footage, age, property class, and more)

Where the property sits in the county’s structure of townships and neighborhood codes

For most residential property, the assessed value is usually about 10% of the estimated market value. For commercial property, it is typically about 25% of the estimated market value, under Illinois law. Those percentages are important when you’re checking whether your tax bill makes sense.

Each property also has a unique identifier called a Property Index Number, or PIN. You can search by address, find your PIN, and then use the PIN to unlock more detailed information and tools.

Everything in a Cook County IL property search basically revolves around three things:

Finding the right property record (by address or PIN)

Understanding what the record is telling you (values, characteristics, and neighborhood context)

Using that information to make decisions (appeals, exemptions, buying, selling, or budgeting)

The rest of this guide follows that flow step by step.

Start Here: Use the Official Address Search to Find a Property

Most people begin with an address, not a PIN, so the best starting point is the Assessor’s official address-based search page. You can go straight there using the official Cook County Assessor address search tool at the Cook County Assessor’s Office website:
Cook County Assessor address search tool.

This is the core of your Cook County IL property search. On that page, you’ll see a form that asks for:

House Number
Optional direction (N, S, E, W, NE, NW)
Unit Number (if applicable)
Street Name (without “Street,” “St.,” “Avenue,” “Ave.,” etc.)
City

You’ll also need to complete a simple CAPTCHA to confirm you’re not a bot.

Step-by-step: Running a basic address search

Enter the house number (for example, 1234).
If your address has a direction (like N, S, E, W, NE, NW), choose it from the drop-down.
Type only the street name. If you live on “Main Street,” just enter “Main.”
If you live in a condo or multi-unit building, add your unit number in the proper field.
Enter the city (for example, Chicago, Skokie, Markham).
Complete the CAPTCHA.
Click Search.

If the system finds a match, you’ll see property search results for that address, including the PIN and a way to click into more detailed information.

When the property doesn’t show up

Sometimes, especially with condos, corner buildings, or unusual address formats, the property you expect doesn’t appear right away. Try these troubleshooting tips:

Drop the unit number and search for just the building’s street address. Then select the correct unit from any list or details view, if available.

Double-check the street direction. In Chicago, “W 1234 Main” and “E 1234 Main” are entirely different locations.

Simplify the street name (for example, “Old Orchard” instead of “Old Orchard Road”).

Confirm the city name you’re using matches how the county records it (for example, “Chicago” vs. a neighborhood name).

Once you have a successful address search result, make note of your 14-digit PIN. That number unlocks deeper tools and more detailed property data.

Go Deeper: Use Property Details and PIN Lookup to Understand Your Home

After you’ve located your property by address, your next move should be to dig into the property details using the county’s dedicated database. The Assessor Property Details search site lets you search by address or PIN and view a wealth of information about your property:
Assessor Property Details search site.

On that site, you can:

Search by Address or PIN
View the estimated market value and assessed value
See property characteristics, such as building type, square footage, and age
Review information about permits, divisions, and consolidations
See whether certain exemptions (such as a Homeowner Improvement Exemption) are showing
Access Neighborhood Sales data for your property’s neighborhood over the last 36 months

This is the heart of any serious Cook County IL property search because it’s where you see how the Assessor’s Office arrived at its value.

Break down the numbers: Estimated market value vs. assessed value

Once you’re in the property details:

Look for the estimated market value. This is the Assessor’s best estimate of what your property would sell for in the current real estate market, based on mass appraisal models and sales trends.

Find the assessed value. This is usually 10% of the estimated market value for residential property and typically 25% for commercial property.

For example, if the estimated market value is $300,000 for a residential home, you would expect an assessed value around $30,000. If that ratio looks very different, it can be one sign that further investigation or an appeal might be worth considering.

Locate your township and neighborhood code

For assessment purposes, Cook County is divided into 38 townships, and within each township, properties are grouped into neighborhood codes. Those codes matter because:

They show which neighborhood sales the Assessor uses to value your home.
They affect which properties are considered “comparable” for appeals.

You can find your township and neighborhood code on your Reassessment Notice or by checking the county’s property details page on the Assessor’s website, which offers another way to access detailed records:
Assessor’s property details page.

Keeping track of your township and neighborhood code will help when you move on to comparables, appeals, and neighborhood-level data.

See the Big Picture: Map Your Property and Compare Nearby Homes

Sometimes plain numbers aren’t enough. You want to see how your property sits in relation to others in the neighborhood, and whether similar homes have similar assessments. For that, Cook County provides an interactive mapping system known as Cook Viewer.

You can launch the Cook County Cook Viewer interactive map directly from the county’s GIS site:
Cook County Cook Viewer interactive map.

How to use Cook Viewer for property comparisons

Once Cook Viewer is open:

Enter your address or PIN in the search box.
Click on your property on the map.
Select “Compare this Property” (or similar comparison function).

The system then automatically filters for properties that are comparable to yours based on:

Neighborhood
Property class
Square footage
Age

Comparable properties appear on the map, and you can click each parcel to see its characteristics and assessment information. This is extremely helpful if you’re checking whether your assessment is in line with similar homes nearby.

Neighborhood search as a quick comparison shortcut

You might also see references to “Neighborhood Search” when learning about comparables. The Assessor’s site includes a neighborhood-focused search option that lets you look at properties within a specific neighborhood, which some owners use as another way to spot potential comparables:
Neighborhood search section of the Assessor’s site.

Keep in mind, though, that just sharing a township, neighborhood code, and class doesn’t automatically make two properties truly comparable. Characteristics like square footage and age still matter, which is why Cook Viewer (with filters applied) is often the recommended approach.

Use Market Data and Home Value Tools to Check Your Assessment

A thorough Cook County IL property search isn’t just about your single parcel; it’s about understanding the broader market trends that may be driving your value.

From the Assessor’s perspective, assessments should fairly reflect market values. The office estimates those values using mass appraisal models that analyze sales trends across neighborhoods and property types.

Neighborhood sales through the property details system

Inside the property details system, one powerful feature is the Neighborhood Sales function. For your property’s neighborhood code, you can usually see real estate transactions from the last 36 months. This helps you:

Understand how sale prices in your immediate area have moved over time
See whether your estimated market value looks high or low relative to actual sales
Prepare supporting information if you decide to file an appeal

Because the sales are filtered to your neighborhood, they’re more relevant than random listings or distant comparables.

Use official home value reports for a wider perspective

If you want to zoom out beyond your specific property, the Assessor’s Office publishes reports showing how values are trending. The county provides a dedicated Home Value Report where you can review broader valuation patterns and context:
Home value report from the Assessor’s Office.

These reports don’t replace your own property details, but they can help you understand:

Why certain neighborhoods may have seen bigger increases or decreases
How residential and commercial values compare
How your area fits into county-wide trends

The combination of your property details, neighborhood sales, and official reports gives you a robust, data-driven picture of how your value was determined.

Turn Your Property Search into a Strong Property Tax Appeal

Once you complete a careful Cook County IL property search, you may conclude that your home or business property is fairly assessed—or you may feel it’s too high. If you believe the Assessor’s market value estimate is above what your property is really worth, or not uniform compared to similar properties, you have the right to file an appeal.

Know when you can appeal: Check the assessment calendar

Appeals in Cook County can only be filed during specific windows, which vary by township and by year. To see when your township is open for appeals, review the Assessor’s official Assessment and Appeals Calendar:
Assessment and Appeals Calendar from the Assessor’s Office.

On that calendar, you can:

Look up your township
See deadlines for when assessment notices were mailed
Note the appeal filing period
Confirm when appeal decisions are expected

Because the calendar is time-sensitive, check it before you spend a lot of time preparing an appeal to make sure your filing window is open.

File online using your research and comparables

When you’re ready, the Assessor’s site allows property owners to file appeals electronically. You can use the online appeals portal to submit your information directly:
Online appeals portal for property owners.

As you complete your appeal:

Use your property details (estimated market value, assessed value, characteristics) to explain why you believe the value is too high.

Attach information on comparable properties, such as PINs you identified using Cook Viewer, to support a “lack of uniformity” argument.

Reference recent Neighborhood Sales that suggest a lower market value.

Even if you don’t upload comparables yourself, the Assessor’s analysts will analyze comparable properties in their database. However, bringing your own research from your property search can help you clearly tell your side of the story.

Get In-Person Help with Your Cook County Property Search

Not everyone wants to navigate property searches, home value reports, and appeal forms on their own. The Cook County Assessor’s Office provides in-person support at multiple locations throughout the county, and you can also meet with staff by appointment.

For many owners, especially those dealing with complex issues like Certificates of Error, property class questions, or commercial properties, it can be very helpful to sit down with someone from the Assessor’s team. Staff can:

Help you locate your property record and PIN
Walk through your property characteristics and assessment
Explain what you’re seeing in your Cook County IL property search results
Talk through exemption questions and appeal options

To see where you can visit and which branches are available, review the official Assessor’s Office Locations page for current locations and hours:
Assessor’s Office locations listing.

You can also schedule an appointment from the Assessor’s website if you prefer to pick a specific time before traveling to an office.

Final Check: Make Sure Your Information Matches Across All Systems

As you wrap up your research, it’s smart to make sure the information you see is consistent across the different official property search tools:

The address search you started with should match the property characteristics in the detailed records.

The Assessor Property Details system should show the same PIN and core information as what appears on your reassessment notice or tax bill.

The Cook Viewer map should place your property in the correct location, with the same class and basic details.

Any Neighborhood Sales in your property details should look reasonable for your area once you compare them to your assessed value.

Because online systems can occasionally be updated, or data can change after a correction or appeal, it’s a good habit to re-run a quick Cook County IL property search after major changes—such as after an appeal decision or significant renovation—so you always know what the county currently has on file.

Property Search–Related Departments and Offices

Cook County Assessor’s Office, 118 North Clark Street, Room 320, Chicago, IL 60602, (312) 443-7550

Markham Branch Office, 16501 S. Kedzie Avenue, Room 237, Markham, IL 60426, (312) 443-7550

Skokie Branch Office, 5600 West Old Orchard Road, Room 149, Skokie, IL 60077, (312) 443-7550

Bridgeview Branch Office, 10200 South 76th Avenue, Room 237, Bridgeview, IL 60455, (312) 443-7550

Cook County Property Search FAQs

How do I start a Cook County Illinois property search with just an address?

If you only have a street address, use the Assessor’s official Search by Address page. There you’ll enter your house number, optional direction, street name (without “Street,” “Road,” etc.), unit (if any), city, and complete a quick CAPTCHA before hitting Search. This will return the matching parcel and show the Property Index Number (PIN) you’ll use for deeper research. You can begin here on the Search by Address page.

How can I see detailed information once I’ve found my property?

After you have your PIN or confirmed address, go to the Assessor’s enhanced Property Details tool. It pulls information directly from the Assessor’s database, including estimated market value, assessed value, building characteristics, and a “Neighborhood Sales” section with recent sales in your property’s neighborhood code. This is the main place to review how your property is being treated in the assessment system: visit the Assessor’s Property Details tool.

Can I search Cook County properties by PIN instead of address?

Yes. If your tax bill or prior assessment notice lists the 14-digit PIN, you can skip the address fields and search by PIN alone. The Assessor’s site provides dedicated PIN search options, including the main Property Details search and advanced 10-digit or 8-digit PIN tools. A convenient starting point is the Find out more information about your property page, which links directly into the PIN-based search screens.

How do I find comparable properties when reviewing my search results?

To see how your property stacks up against similar ones, the Assessor recommends using Cook Viewer, an interactive county GIS map. After launching it, search by your address or PIN, click your parcel, and use the comparison function to highlight properties with similar class, square footage, age, and neighborhood. This is especially useful if you’re evaluating uniformity for a possible appeal. You can launch Cook Viewer directly from the Assessor’s website.

Where can I get in-person help with my property search?

If online tools leave you with questions, you can meet with Assessor’s Office staff at the downtown office or branch locations in the suburbs. The locations page lists each office and current hours, and you can also schedule a visit online before you go. For the latest information on where to go and how to plan your visit, check the official Assessor’s Office Locations page.