Orland Park 2026 Reassessment: Property Tax Proration Explained

Orland Township reassessment notices went out on September 24, 2026. Homeowners have until November 6 to appeal to the Cook County Assessor. The Assessor says the market values on those notices will show up on tax bills in 2027. A house going under contract in Orland Park this month will most likely close before any of that reaches a bill. At closing, the property taxes get split between seller and buyer using a bill built on the township's 2023 valuation.

Under the standard Chicago-area contract, that split is final once the deal closes. The change from the reassessment, in either direction, belongs to whoever owns the home when the Tax Year 2026 second installment arrives in 2027. In nearly every transaction, that's the buyer.

Which bill a fall closing actually uses

Cook County bills taxes a year behind. Taxes for 2025 are billed and paid in 2026. The first installment is an estimate equal to 55% of the prior year's total. The updated assessment, rates and exemptions only show up on the second installment. Orland's last reassessment was in 2023, and 2026 is its first scheduled reassessment since then.

Lined up together, the bills look like this:

The Tax Year 2025 second installment was late this year. Cook County announced a two-month delay tied to a technology overhaul. The county scheduled the bills for September 1, 2026, with an October 1 due date. The Assessor reported that the bills went out that day. Until those bills were released, the latest complete bill for an Orland Park home was Tax Year 2024. The Tax Year 2025 bill is now the latest complete one. It's also the last Orland bill based on the 2023 valuation, and every closing between now and the 2027 second installment will use it.

The blank in Paragraph 12

The Multi-Board Residential Real Estate Contract 8.0, published by the Chicago Association of REALTORS, handles general real estate taxes in Paragraph 12(a):

"The general real estate taxes shall be prorated to and including the date of Closing based on ___ % of the most recent ascertainable full year tax bill. All general real estate tax prorations shall be final as of Closing, except as provided in subparagraph b) below or as otherwise agreed by the Parties in writing."

Since the buyer pays the bill that arrives after closing, the seller gives the buyer a credit at closing. That credit covers the seller's share of the current year's unpaid taxes and is estimated from the latest full-year bill. The percentage in that blank decides how closely the estimate tracks the bill that eventually arrives. Subparagraph 12(b) only covers homes that weren't taxed for the full year as currently improved, such as new construction. For those homes, 3% of the purchase price goes into escrow and the taxes are re-prorated later. An Orland Park home that has been taxed for a full year in its current form falls under 12(a). Unless the parties agree otherwise in writing, the figure set at closing is the final one.

Illinois real estate attorneys don't agree on a standard percentage. Braverman & Makhlouf calls 100% common in years when assessments are stable and lists 105% to 110% as options when an increase is expected. The Berardi Law Office describes 105% as the usual figure, with 110% as a cushion in reassessment years. Attorneys also describe two alternatives: estimating the credit from the new assessment, or agreeing in writing to re-prorate or hold money in escrow once the actual bill comes out.

The dollar amounts are easy to work out. On a $9,000 full-year bill, every five percentage points is $450 of a full year's taxes. The seller's share is prorated by how much of the year has passed, so a closing in late fall uses most of that amount. This is one of the few lines in an Orland Park negotiation where the size of the coming change can be estimated, because the notices are already out.

A 20% assessment increase doesn't mean a 20% tax increase

The headline number from the notices is large. A Cook County tax-appeal firm reviewed Assessor files for Orland Township in a September 29, 2026 analysis. Across 37,567 homes, it found the median assessment up 19.9% from the final 2025 value to the 2026 notice. Total residential assessed value rose 20.8%, and 98.8% of homes went up. The township includes Orland Park and Orland Hills, plus parts of Tinley Park and Palos Park.

Taxing districts set their levies first. Rates are then calculated by dividing those levies over the whole assessed base. When nearly every home's assessment rises by about the same amount, the rate drops and each home's share of the levy barely changes. The same analysis makes that point and adds that a home up 30% in a township up 20% ends up paying a bigger share of the same levy. The Assessor says the same thing in its own words: a property's tax effect "is impossible to predict based on just one property's change in assessed value."

That makes 20% the baseline to compare against. The number that matters for a particular house is how its increase compares with that baseline and with the other property in its taxing districts. Homes are usually assessed at 10% of market value and most commercial property at 25%, before equalization and exemptions. Here are the firm's medians for 2025 to 2026 by property class:

On the initial notices, the median home rose faster than the median commercial parcel. Medians don't show each class's total assessed value, though, and each property's share of the levy depends on that total, so these figures can't show how the levy will be divided. The figures will also change before any bill is calculated. The Assessor's commercial page lists an October 15, 2026 appeal deadline, three days from now. Homeowners have until November 6. The Assessor's worksheet for income-producing property lists one retail parcel at 55 Orland Square with an initial market value of $109.728 million. That covers one parcel, not the whole mall, and it's the kind of figure that tends to change on appeal.

The size of the jump comes from timing more than from overvaluation. The Assessor's township table shows Orland's median single-family sale price at $405,000 in 2025, with a 2026 Assessor estimate of $408,000. For condos, the median sale was $264,000 against an estimate of $253,000. The 2026 notices mostly bring three years of sales since the 2023 valuation into the numbers at once. Last year's bill still uses the older values, and that's the bill a closing this fall is prorated on.

The exemption line that drops off when a home sells

The bill a buyer sees in a listing packet reflects that seller's exemptions. The Assessor notes that a notice or bill shows exemptions applied in past years. A new owner has to apply for their own. The Cook County Treasurer says automatic renewal of the Homeowner Exemption stops when a property sells. The Homeowner Exemption requires that the owner live in the home as a principal residence. The Senior Exemption also requires the owner to be 65 or older. In the tax-appeal firm's example for a median Orland home, the Homeowner Exemption took about $900 off the bill.

The contract covers the seller's side of this. Paragraph 12(a) says that if the bill used for proration reflects a homeowner, senior or other exemption, the seller will file what's needed to preserve it. It also says the proration "shall not include exemptions to which the Seller is not lawfully entitled." Nothing in the contract carries those exemptions over to the buyer's future bills. A buyer's first full bill in the home can include the reassessment and leave out exemptions the seller had. That bill will be larger than either change would produce alone.

How sellers fit into the same timeline

For an Orland Park homeowner who plans to list in the next year, the November 6 deadline is the Assessor-level appeal window for the value that will drive the 2027 bills. A buyer who knows this timeline may bring up the reassessment when negotiating the proration percentage. A seller who has the notice, knows how the home's change compares with the roughly 20% township median, and knows whether an appeal is pending can answer with numbers instead of guesses.

The township page includes an interactive map that compares sales with the Assessor's estimates by neighborhood code. Every reassessment notice lists that code. Pulling that comparison for a specific block takes a few minutes and makes the proration discussion much more concrete for both sides.

A few questions that come up

Will the 2027 first installment show the reassessment? No. The first installment is 55% of the prior year's total, so the Tax Year 2026 first installment is based on the Tax Year 2025 bill. The reassessment shows up on the second installment.

Is the assessment notice the same as a tax bill? No. The final bill also depends on levies, rates and exemptions, and none of those are set yet.

Does all of this apply to Orland Park condos? Yes, the timeline is the same. The Assessor's 2026 condo estimate of $253,000 is below the 2025 median condo sale of $264,000. That's a different starting point from single-family homes, where the estimate is slightly above 2025 sales.

Can the parties agree to re-prorate after the real bill comes out? Paragraph 12(a) allows changes "as otherwise agreed by the Parties in writing." Whether to do that and how to word it is a question for each party's real estate attorney.

If you're buying or selling in Orland Park before the 2027 bills arrive, Sullivan Property Group can sit down with you, your 2026 reassessment notice and the latest Tax Year 2025 bill. We'll compare your home's change with the township median and walk through what each proration percentage would mean in dollars. Schedule a consultation and you'll have those numbers before you start negotiating.

This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.