Cook County 2025 Triennial Reassessment: What North Suburban Property Owners Need to Know

The 2025 triennial reassessment of Cook County's north suburban townships is complete, and the numbers are striking. Assessments across northern Cook County grew between 18 and 40 percent on average, affecting property owners in Barrington, Evanston, Elk Grove, Hanover, Leyden, Maine, New Trier, Niles, Northfield, Norwood Park, Palatine, Schaumburg, and Wheeling townships.

If you own residential or commercial property in any of these townships, these increased assessments will directly affect the second installment property tax bill issued in 2026. Understanding what happened and what you can do about it is essential.

What the 2025 Reassessment Means for Your Tax Bill

A higher assessment does not automatically mean a proportionally higher tax bill. Property taxes are determined by the interplay between your assessed value, the state equalization factor, applicable exemptions, and the tax rates set by local taxing bodies. However, if your assessment increased more than the average in your taxing district, your share of the total tax levy will likely increase.

For many north suburban homeowners, the combination of rising assessments and steady or increasing local levies will translate into noticeably higher bills when the second installment arrives in mid-2026.

The Appeal Window Is Still Open

Even though the Assessor's initial filing deadlines for many north suburban townships have passed, several important opportunities remain. The Board of Review opens its own filing periods for each township after the Assessor's process concludes. These Board of Review deadlines are separate from the Assessor's deadlines, and filing at the Board is free.

If you missed the Assessor's deadline for your township, the Board of Review is your next opportunity. And if you already filed with the Assessor and received an unsatisfactory result, you can file a separate appeal with the Board of Review as well.

Who Should Appeal

You should seriously consider appealing if your assessment increased by 20 percent or more, if your estimated market value on the reassessment notice exceeds what you believe your property would actually sell for, if comparable properties in your neighborhood are assessed at lower values per square foot, or if your property has condition issues, vacancy, or other factors that negatively affect its value.

Commercial property owners and owners of multi-unit residential buildings in the north suburbs should be particularly attentive. The Assessor's Office now requires verifiable income and expense documentation for business properties, and providing accurate financial data can significantly influence the outcome of your appeal.

Evidence That Supports a Strong Appeal

For residential properties, the most effective evidence includes recent sales of comparable homes in your area that sold for less than your assessed market value, documentation of property condition issues that reduce value, and proof that the Assessor's property characteristics are incorrect, such as wrong square footage, room count, or building age.

For commercial and multi-unit properties, actual income and expense data is critical. Rent rolls, lease agreements, operating statements, and vacancy documentation all help establish that the assessor's estimated value exceeds what the property is actually worth based on its income-producing capacity.

Planning Ahead for 2026

If your township's 2025 appeal windows have fully closed, you can register early for a 2026 appeal. In non-reassessment years, the Board of Review still opens filing periods for every township, and you can challenge your assessment annually. The sooner you begin preparing documentation, the stronger your case will be when the window opens.

Professional Guidance Makes a Difference

The property tax appeal system in Cook County is complex, with multiple agencies, different filing deadlines, and varying evidentiary standards at each level. An experienced property tax attorney can evaluate whether your assessment is likely to be reduced, identify the strongest arguments for your specific property, and ensure that deadlines are met and documentation is properly prepared.

Contact Younis Law Group for a free assessment review. Whether you own a single-family home in Palatine or a commercial building in Schaumburg, we can help determine whether an appeal makes financial sense and handle the process on your behalf.