By Lauren Victory

CHICAGO (CBS) — Every year, concern grows among homeowners throughout Cook County as property tax bills come in. The high bills could have to do with the county’s assessed value of your home.

Properties in Cook County are reviewed every three years. The schedule depends on location.  Northern suburbs were assessed this year, Southern suburbs will be assessed next year and Chicago will be assessed in 2021.

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However, homeowners can appeal property taxes every year; and some experts suggest doing just that. Acting fast is key, because when it is your area’s turn to appeal, the window is about a month long.

The Cook County Assessor uses similar homes to determine your home’s fair market value, which is then used in local tax formulas. Note that a neighbor might have a similar home but pay a lower amount of taxes because he or she took advantage of exemptions.

Tax bills might increase if there’s a change in tax rates; but taxes also rise if the real estate market goes up, because that affects the value of a home.

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If you feel the Cook County Assessor overvalued your home, you have the right to appeal. This can be confusing.

First off, remember 2019 tax bills are actually for 2018 taxes, and if the 2019 bill is higher because of an increase in home value in 2018, the best time to appeal would have been last year. You should have received an assessment notice from the Cook County Assessor’s Office.

If you appeal now and win, you’ll still have to pay those hefty 2019 taxes. The lower tax bill won’t come until the later half of 2020. There’s an option to file a Certificate of Error to “correct” 2019 taxes, but that requires even more documentation and will only kick in if there is factual inaccuracy such as a mistaken calculation of square footage or an error in property classification.

The appeals window opens and closes quickly. For example, assessment notices for Calumet homeowners were mailed on June 14. The deadline to file an appeal was July 15. Pay attention to the Assessor’s website. Deadlines vary based on location. Hyde Park assessment notices were mailed a little over a week ago. Property owners there can file an appeal up until Aug. 12.

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If you miss your Assessor’s Office deadline, you can file an appeal with the Cook County Board of Review but that’s a whole other story.

Lauren Victory