Buying the house is the loud part. The property tax adjustment is the quiet part that shows up later.
If you just bought in Cook County, do not wait for the next big tax bill before you look at the assessment. Your purchase may be useful evidence, but it is not the only thing that matters.
Start with the county's current record. Make sure the PIN, property class, square footage, building description, and exemptions make sense. If the county thinks your home is bigger, newer, or improved in ways it is not, your purchase price may not be the main story.
Then check the appeal calendar. Cook County appeals run by township, and the Assessor's assessment and appeal calendar is the place to confirm when your window opens.
Next, think about your sale.
Was it an arm's-length sale? Was it listed on the open market? Were there seller credits, major repairs, family terms, foreclosure issues, or other facts that explain the price? The cleaner the sale, the easier it is to use as evidence.
The Assessor's official appeal rules matter here because an appeal is not just "I paid less, so lower my taxes." It is a valuation argument. Your sale is one piece of that argument.
New buyers also need to check exemptions. If the prior owner had exemptions you do not qualify for, your next bill may rise even if the assessment did not go crazy. If you qualify for your own exemption, make sure it is applied when it should be.
The biggest mistake is assuming the closing table handled everything. It did not.
The closing statement handled credits between buyer and seller. It did not guarantee your next assessment is fair. It did not guarantee your exemptions are right. It did not build your appeal evidence for you.
So yes, new buyers should check appeal potential. Not because every new buyer should file, but because the first year is when surprises get expensive.
Look it up now, while the paperwork is still easy to find. A Censum check gives you a cleaner read before the bill becomes a monthly-budget problem.