Comparing a home in Mokena to one in Orland Park? The property taxes alone can shift your monthly payment more than you expect. If you are shopping near the county line, you want a clear picture before you fall in love with a house. This guide explains how Illinois property taxes work, what differs between Will and Cook counties, and how to estimate your monthly escrow so you avoid surprises. Let’s dive in.
How Illinois property taxes work
Illinois property taxes follow a three-step path that turns market value into your annual tax bill.
- Market value → Assessed value: For most residential property, the assessed value equals 33.33% of market value.
- Assessed value → Equalized Assessed Value (EAV): The assessed value is multiplied by an equalization factor set to keep assessments uniform. The factor can vary by county and year.
- EAV → Annual tax bill: EAV is multiplied by the combined tax rate from all taxing districts serving the parcel, such as schools, municipal, park, library, fire, and special districts.
In short: Market value × 33.33% = assessed value. Assessed value × equalization factor = EAV. EAV × combined tax rate = annual tax. An EAV-based rate around 5.4% often works out to about 1.8% of market value because EAV is roughly one-third of market value.
Will vs. Cook: what actually differs
Both counties use the same statewide framework. The differences you feel as a buyer come from how each county administers the process, plus the local mix of taxing districts that apply to a specific parcel.
Assessment notices and appeals
Each county sets its own assessment notice schedule and appeal windows. You should check the current timelines on the county assessor’s website. Both counties provide an appeal path through the assessor or a Board of Review, but filing windows and documentation requirements can differ.
Exemptions and transfers
Both counties offer common Illinois exemptions, including the homeowner’s (general homestead), senior, disabled person, disabled veteran, and senior assessment freeze where available. Application methods and timing can differ by county. Exemptions usually do not transfer automatically at sale, so you should plan to apply after closing if eligible and confirm when the exemption will first appear on your bill.
Billing and installments
Both counties issue annual property tax bills, often in two installments. Due dates and grace periods can vary by county and year. Always confirm the current year schedule on the county treasurer’s site and ask your lender how they will handle estimated installments in escrow.
Taxing districts drive differences
The largest driver of bill differences is the specific combination of local taxing districts tied to each parcel, especially school districts. Mokena and Orland Park can look similar on a map, but they are served by different mixes of school, park, library, fire, and special districts. Two homes with similar prices can have very different tax bills because their district mix and levies are not the same.
Mokena vs. Orland Park: what to check
If you are weighing a Mokena home in Will County against an Orland Park home in Cook County, focus on parcel-level details.
- Confirm assessed value, EAV, and exemptions on each county’s assessor portal.
- Review the most recent tax bill on the county treasurer site and note the taxing districts listed.
- Ask whether the seller was receiving any exemptions and if you will need to apply for your own after closing.
- Ask your lender for an escrow estimate using the latest actual tax bill for each home.
How to compare two homes step by step
- Get the seller’s last two tax bills or look them up by parcel ID on the county treasurer’s site.
- Look up the parcel on the county assessor portal and confirm assessed value, EAV, exemptions, and the list of taxing districts.
- Note the combined tax rate or the sum of levies that produce the total bill.
- Confirm which exemptions will apply to you and when they will show on your bill.
- Ask your lender to run an escrow analysis using the latest bill and their cushion policy.
- Check whether a reassessment is scheduled or recently occurred in the area, which can affect future bills.
Illustrative payment examples
Here is a simple, illustrative example so you can see how monthly payments can differ even between nearby towns. Use your parcel’s actual data for decisions.
Assumptions:
- Purchase price = $400,000
- Assessment level for residential = 33.33%
- Equalization factor = 1.00
- Combined EAV-based rate = 5.5% for a Will County example parcel and 6.5% for a Cook County example parcel
Calculations:
- Assessed value = $400,000 × 33.33% = $133,332
- EAV = $133,332 × 1.00 = $133,332
- Annual tax at 5.5% = $133,332 × 0.055 = $7,333 → about $611 per month
- Annual tax at 6.5% = $133,332 × 0.065 = $8,666 → about $722 per month
Result: That difference is about $1,333 per year, or roughly $111 per month. Your actual numbers depend on the parcel’s combined rate and any exemptions that apply.
Escrow, proration, and closing
Most lenders require an escrow account for taxes and insurance. Your monthly escrow payment equals the estimated annual taxes and insurance divided by 12, plus any lender cushion. Under federal rules, lenders can collect up to a two-month cushion, though some collect less.
At closing, taxes are typically prorated between buyer and seller based on the period of ownership. Your lender may also collect several months of taxes to fund the escrow account. If the tax bill increases later due to reassessment or levy changes, your lender will adjust the escrow, which can increase your monthly payment.
Why tax surprises happen
- Exemptions do not transfer automatically. If the seller had benefits you do not yet have, the next bill can be higher until you apply and the exemption is processed.
- Local levies change. School or municipal levy increases, including bonds, can raise bills.
- Reassessment can change your EAV. If values in the area rise, assessments may follow.
- Parcel-specific districts matter. Relying on a townwide “rate” can miss special districts or bonds tied to a specific parcel.
Buyer checklist before you offer
- Get the last two years of tax bills and confirm payment status.
- Look up the parcel on the county assessor and treasurer portals to confirm EAV, exemptions, and taxing districts.
- Identify the school district and check for recent bond measures or levy changes.
- Ask which exemptions the seller had and plan to file for your exemptions after closing if eligible.
- Request a lender escrow estimate using the actual tax bill and the lender’s cushion policy.
- Confirm tax proration with your closing team and how any unpaid taxes will be handled.
Work with a local advisor
A clear tax comparison lets you budget with confidence and choose the right home for your goals. If you are debating Mokena in Will County versus Orland Park in Cook County, we can help you pull parcel records, verify exemptions, and get accurate escrow estimates before you write an offer. Reach out to the concierge team at Niki Rocco to make your next move with clarity and care.
FAQs
Do county lines alone determine taxes in Mokena vs. Orland Park?
- No. County administration differs, but the biggest drivers are the specific taxing districts that serve the parcel and whether your exemptions apply.
How do you calculate Illinois property taxes on a new purchase?
- Multiply market value by 33.33% to get assessed value, apply the equalization factor to get EAV, then multiply EAV by the parcel’s combined tax rate.
What happens to exemptions after I buy in Will or Cook County?
- Most exemptions do not transfer automatically, so you should apply after closing and confirm when the benefit will first appear on your bill.
How will property taxes affect my mortgage escrow in Mokena?
- Your lender will divide the estimated annual tax by 12 for a monthly deposit and may add up to a two-month cushion, which is often collected at closing.
Can I appeal my assessment in Cook or Will County?
- Yes. Both counties allow appeals through the assessor or Board of Review within set windows, so check the current year schedule and gather supporting evidence.
