Let’s Talk About Real Estate: Why Your Property Tax Assessment Matters When You Own a Home

Buying a home is often focused on the purchase price, interest rate, and monthly mortgage payment. But there is another number homeowners should keep an eye on after closing: the assessed value of their property.

Your property’s assessed value is used to determine your property taxes, and it is not necessarily the same as what your home would sell for on the open market.

Understanding the difference can help homeowners recognize changes in their tax bill, plan for future expenses, and know when it may be worth taking a closer look at their assessment.

What Is a Property Tax Assessment?

A property tax assessment is an estimated value assigned to your property for taxation purposes.

The assessor considers factors such as the property’s characteristics, improvements, and market conditions. That assessed value is then used along with applicable local tax rates to calculate your property taxes.

One important distinction: an assessment is not the same thing as a home appraisal or a current market value.

An appraisal is generally completed for a specific purpose, such as obtaining a mortgage, and is an opinion of market value as of a particular date. A property tax assessment, on the other hand, is part of the local taxation process.

Missouri and Illinois Handle Assessments Differently

For homeowners across St. Louis, the Metro East, and Central Missouri, it's especially important to remember that property tax systems are not identical across state lines.

In Missouri, real property is generally reassessed on a two-year cycle, with real property assessed as of January 1 of odd-numbered years. The assessed value generally carries into the following even-numbered year unless circumstances such as new construction or improvements affect the property.

In Illinois, property is generally viewed, inspected, and revalued once every four years, although the schedule can vary by county and Cook County follows a three-year cycle. Assessors may also revalue property between general assessments when appropriate.

That difference is one reason homeowners should pay attention to the rules in the county where their property is located rather than relying on what a friend or family member experienced somewhere else.

Why Can Your Assessment Change?

There are several reasons your assessed value may change.

Your local market has changed

If property values in your area have increased, your assessor's valuation may reflect changing market conditions.

That does not automatically mean your home would sell for exactly that amount. Assessment and market value are related, but they serve different purposes.

You've made improvements

Adding finished living space, remodeling, constructing an addition, or making other significant improvements can affect a property's value for assessment purposes.

In Missouri, for example, new construction and improvements can affect the property's assessed value even during the year between regular reassessments.

Your property record may have changed

Assessors rely on property information when determining value. If information about your home is incorrect, such as square footage, finished space, or other characteristics, it can be worth contacting the appropriate assessor's office to make sure the record is accurate.

What If You Think Your Assessment Is Too High?

First, don't automatically assume that a higher assessment means your taxes will increase by the exact same percentage.

Your property tax bill depends on more than the assessed value. Local tax rates and the various taxing districts that apply to your property also play a role.

If you believe your assessment does not accurately reflect your property, start by reviewing the property record and learning about your county's appeal process.

In Illinois, for example, homeowners appeal the assessed value, not the tax bill itself. The Illinois Department of Revenue also notes that the appeal process begins locally.

Missouri homeowners likewise have an established process for challenging property assessments through the local Board of Equalization and, when applicable, the State Tax Commission.

A Few Things Homeowners Should Keep in Mind

Don't confuse assessed value with market value.
Your tax assessment isn't necessarily an indication of what your home would sell for today.

Don't ignore changes in your tax bill.
If your payment changes because your lender adjusts your escrow account, look at the reason for the change. Property taxes may be part of the explanation.

Keep an eye on your property record.
It's a good idea to periodically review the information your county has on file for your property.

Know your local rules.
The process can vary significantly between Missouri and Illinois and even from one county to another.

Ask questions when something doesn't look right.
Your county assessor's office is the appropriate place to start when you have questions about your property's assessment or record.

How This Connects to Buying or Selling a Home

Property taxes are one of the ongoing costs of homeownership, so they deserve attention when you're evaluating a property.

For buyers, looking only at the purchase price and estimated mortgage payment doesn't tell the entire story. Property taxes, insurance, HOA fees, utilities, and maintenance can all contribute to the actual cost of owning a home.

For sellers, understanding your property's tax information can also help you answer questions from prospective buyers and better understand the financial picture surrounding the property.

And when you're comparing homes in different counties or even across the Missouri-Illinois border, it's important to look beyond the list price.

The Bottom Line

Property taxes aren't the most exciting part of homeownership, but understanding how your property is assessed can save you from surprises and help you make more informed decisions.

Whether you're buying your first home in St. Louis, selling in the Metro East, investing in Central Missouri, or purchasing a home around Lake of the Ozarks, Jefferson City, or Columbia, having a clear picture of the ongoing costs is an important part of making a smart real estate decision.

Real estate doesn't end at the closing table. Understanding what comes after closing is just as important.