A property tax increase in McHenry County almost always traces back to one of two things: the taxing districts that cover your address asked for more money this year, or the assessed value of your home went up. Often both move at once. Understanding which driver is pushing your bill higher tells you where to look for relief, whether that means claiming an exemption you’ve missed, filing an appeal, or planning for a referendum-funded project that will stay on your bill for years.
The Two Reasons Your Bill Went Up
Every school district, fire protection district, library, park district, and the county itself files an annual levy with the McHenry County Clerk. The levy is the dollar amount each body says it needs for the coming year. The clerk spreads each levy across the taxable property inside that district’s boundaries, and your share depends on what your property is worth compared to everyone else’s in the same district.
Most homes sit inside ten or more overlapping districts. School districts usually take the largest slice, often more than half the bill. If any one of those bodies raises its levy, your bill climbs even if your assessment stayed flat. If your assessment also rose, the two effects compound.
Why the Tax Cap Doesn’t Always Hold Your Bill Down
Illinois limits how fast most non-home-rule districts can grow their levies through the Property Tax Extension Limitation Law, usually called PTELL or “tax caps.” The total extension a district collects cannot grow by more than 5% or the prior year’s Consumer Price Index increase, whichever is lower.1Illinois Department of Revenue. What Is the Property Tax Extension Limitation Law (PTELL)?
That cap applies to the district’s overall extension, not to your individual bill. Several things sit outside it. New construction adds to the tax base without being subject to the cap. Voter-approved bond referendums for school buildings or infrastructure are excluded entirely, so if local voters approve a referendum, the debt service rides on top of the capped amount. Annexations can expand a district and shift the burden around. In a year with low CPI growth, a referendum plus new development plus a higher assessed value can still produce a sharp increase on your bill.
How Your Assessed Value Is Built
Township assessors in McHenry County estimate fair market value for every parcel and set the assessed value at one-third of that figure. Illinois law requires most property to be assessed at 33⅓% of fair market value.2Illinois Department of Revenue. What Is the Tax Rate for Property Taxes, and When Do I Have to Pay My Property Taxes? A home the assessor pegs at $300,000 carries an assessed value near $100,000.
Illinois also requires a full reassessment of every property every four years. This is the quadrennial reassessment, and during that year assessors conduct a thorough review to bring values in line with the current market.3Tazewell County. Quadrennial Explanation Between quadrennial years, assessors can still adjust values when building permits show significant improvements or when market data moves meaningfully.
The Equalization Factor
Once local assessors finish, the Illinois Department of Revenue checks whether a township’s assessments averaged out to the 33⅓% target. If they ran low, the Department applies a multiplier, called the equalization factor, that bumps every assessment in the township upward. McHenry County’s most recent township equalization factor was 1.0524, with a state multiplier of 1.0000.4McHenry County Illinois. Property Tax 101 A factor above 1.0 means local values were running slightly under the target and were adjusted up. The number that comes out is your Equalized Assessed Value (EAV), which is what the tax rate actually hits.
Improvements That Trigger a Reassessment
You don’t need to wait for a quadrennial year to see your assessment change. Building permits flag improvements the assessor will pick up. Adding square footage, a new bedroom, an expanded kitchen, or a second story almost always increases the assessment. So does converting a garage to living space, installing a pool, or putting up a detached structure with utilities. Solar panels and whole-house generators can also add value. Routine maintenance and cosmetic updates that don’t change the structure or add square footage rarely move the number.
Exemptions That Lower What You Owe
Exemptions reduce your EAV before the tax rate applies, so each dollar of exemption saves you whatever your combined districts charge. McHenry County is classified as contiguous to Cook County, which means the exemption amounts are higher here than in downstate counties. Check your bill against this list: a missing exemption is often the fastest fix for a bill that jumped.
General Homestead Exemption
Any owner using the property as a primary residence qualifies. In counties contiguous to Cook, the maximum reduction is $8,000 off the EAV.5Illinois Department of Revenue. Property Tax Relief – Homestead Exemptions, PTELL, and Senior Citizens Real Estate Tax Deferral Program Apply through the Chief County Assessment Officer with proof of residency such as a driver’s license or utility bill. Once granted, it renews automatically as long as you own and occupy the home.
Senior Citizens Homestead Exemption
Owners 65 or older get an additional exemption worth up to $8,000 off the EAV in McHenry County.6Illinois General Assembly. Illinois Code 35 200 – Senior Citizens Homestead Exemption Proof of age is required on the first application. It stacks on top of the general homestead exemption, so a qualifying senior can see up to $16,000 pulled out of the EAV.
Senior Citizens Assessment Freeze
The freeze locks your EAV at the level it was in the year you first qualified, so future increases don’t push the bill up. Total household income for the preceding year must be $65,000 or less.7St. Clair County, Illinois. PTAX-340 2025 Low-Income Senior Citizens Assessment Freeze Homestead Exemption Application and Affidavit Household income here is broader than federal AGI and includes Social Security, public assistance, and other items that may not appear on a tax return. File Form PTAX-340 with the Chief County Assessment Officer along with Social Security statements and federal returns. The freeze requires annual renewal with updated income verification, and missing the renewal deadline means losing the benefit for that year.
Disabled Persons Homestead Exemption
Homeowners with a disability can receive a $2,000 annual reduction in EAV on a primary residence.8Illinois General Assembly. Illinois Code 35 200 – Homestead Exemption for Persons with Disabilities The first application (Form PTAX-343) requires proof of disability, and the exemption needs annual renewal. A property cannot receive this exemption in the same year it receives the veterans with disabilities exemption.
Veterans with Disabilities Exemption
Relief for veterans with a service-connected disability is tied to the VA rating:9Illinois Department of Revenue. Property Tax Relief – Homestead Exemptions, PTELL, and Senior Citizens Real Estate Tax Deferral Program – Section: Standard Homestead Exemption for Veterans with Disabilities
- 30% to 49% disability: $2,500 reduction in EAV
- 50% to 69% disability: $5,000 reduction in EAV
- 70% or higher: the first $250,000 of EAV is fully exempt from taxation
An unremarried surviving spouse of a veteran killed in the line of duty qualifies for a full exemption on the primary residence, even if the veteran never applied. For tax years 2024 forward, veterans who served during World War II receive a full exemption regardless of disability level.
Appealing an Assessment You Believe Is Wrong
If the assessment looks too high after you compare it to recent sales nearby, you can challenge it through the McHenry County Board of Review.10McHenry Township. Appeals – McHenry Township The appeal must be filed within 30 calendar days after assessment changes are published for the current year. Miss that window and you generally cannot contest the valuation until the next cycle.
The strongest appeals carry hard numbers. Recent sale prices for comparable homes in your township are the most persuasive evidence, ideally properties similar in size, age, condition, and location that sold in the last one to two years. A professional appraisal strengthens the case but adds cost; residential appraisals used for tax appeals typically run several hundred dollars. The Board of Review schedules a hearing, reviews the evidence, and issues a written decision.
If the local board rules against you, the Illinois Property Tax Appeal Board (PTAB) hears appeals from Board of Review decisions. You have 30 days from the date the Board of Review mails its decision to file. PTAB conducts its own independent review and is not bound by the local board’s findings. Further challenges can go to circuit court, though most residential disputes are resolved before that.
Payment Deadlines and What Happens If You Fall Behind
McHenry County property taxes are paid in two installments. The first is due June 10, the second September 10.11McHenry County Illinois. Property Tax Bills Are in the Mail You receive one bill with two coupons. In counties outside Cook, the standard penalty for delinquent taxes is 1.5% per month on the unpaid amount, which compounds quickly over a year.
If you can’t pay in full by the due date, contact the McHenry County Treasurer’s office early. Reaching out before the deadline gives you the best shot at avoiding the worst penalties.
Unpaid taxes eventually land in the annual tax sale, where the county collector applies to the circuit court for a judgment against delinquent properties.12Illinois General Assembly. Illinois Code 35 200 – Property Tax Code, Tax Sales An investor pays the taxes you owe and gets a lien certificate, earning a penalty capped at 9% every six months on the amount paid. You keep ownership during a redemption period of roughly two to three years, during which you can reclaim the property by paying the original taxes plus all accumulated penalties, interest, and fees. Miss the redemption deadline and the tax buyer can petition for a tax deed that transfers ownership. Addressing a delinquent bill early is far cheaper than fighting at the deed stage, and once a deed is issued the loss is permanent.