Travis Bunn

Founder, AppealDesk · Published March 27, 2026 · Updated August 19, 2026

In Illinois, the Tax Bill Your Escrow Pays This Year Was Assessed Last Year, or the Year Before That.

Updated August 2026

Here is the mechanic that trips up most Illinois homeowners with a mortgage: your county does not bill you for this year's assessment this year. Under the Illinois Property Tax Code, the bill your servicer pays out of escrow this calendar year is for last year's assessment (IDOR Publication PTAX-1004; 35 ILCS 200/21-15, 21-30). So when a homeowner wins at the Board of Review in the fall, the natural assumption is that the fix shows up soon. Instead it shows up on next year's bill, which your lender then has to catch on its own separate annual clock.

Layer in one more Illinois quirk: the assessment that produced this year's bill was not necessarily set this year, or even last year. Cook County reassesses one-third of the county each year on a rotating triennial cycle by township group (35 ILCS 200/9-220). Every other county reassesses on a four-year quadrennial cycle (35 ILCS 200/9-215). Between those general reassessments, your assessed value mostly carries forward with an equalization multiplier rather than a fresh look at your property. So the number your escrow account pays this year can trace back to a valuation set one, two, or three years earlier, plus the one-year billing lag on top of that.

Three Clocks, Not One

Texas homeowners deal with a single lag: the gap between an appraisal review board order and their servicer's next escrow analysis. Illinois homeowners deal with three separate clocks stacked on top of each other.

• The reassessment clock. Cook County townships get a fresh, ground-up reassessment once every three years; downstate counties, once every four (9-220, 9-215). In the off years, your assessed value moves mostly by an equalization factor, not a new appraisal of your specific property.
• The arrears clock. Whatever value gets finalized for a given assessment year is not billed until the following year (21-15, 21-30). A Board of Review order signed this November corrects this year's assessment, but the tax bill reflecting that correction is not mailed until next year.
• The escrow clock. Your servicer runs one RESPA escrow analysis per computation year (12 CFR 1024.17(c)(3)), on a schedule tied to your loan, not to the county. It only reacts once it actually sees the corrected bill.

Line those three up and a Board of Review win this year routinely does not reach your monthly mortgage payment until sometime in the year after next, not because anyone made a mistake, but because that is how the calendars stack.

A worked timeline (hypothetical example)

Suppose a homeowner in a downstate quadrennial county gets a township assessment publication in September of Year 1, valuing the home at Illinois' median of roughly $239,000, for an assessed value of about $79,660 at the statewide 33.33% ratio. She files with the Board of Review within the 30-day window and wins a 10% reduction to $215,100 in market value, or about $71,690 assessed. At the state's 2.07% effective rate, that is roughly a $495 annual tax cut. (Rates and reductions vary by taxing district, so treat this as illustration, not a quote.) Here is when that $495 actually shows up:

• November, Year 1: Board of Review issues its decision correcting the Year 1 assessment. Monthly payment: unchanged.
• Spring/summer, Year 2: The county finally mails the Year 1 tax bill, now reflecting the corrected value, because Illinois bills a year behind. Monthly payment: still unchanged.
• Later in Year 2: Her servicer pays that lower bill out of escrow. The account now holds more than it needs, but her payment has not moved yet.
• Her next annual escrow analysis: Whenever that lands on her loan's own computation year, the servicer finally sees the smaller disbursement, projects a smaller Year 3, refunds the surplus, and cuts the monthly payment.

If her analysis date falls early in Year 2, she is still waiting the better part of a year. If it falls late in Year 2 or she has already been analyzed for that computation year, she is waiting closer to two years from the win to the payment change. Nothing in that gap is a servicer error. It is the design.

The Deadline Is Rolling, Not Statewide

Illinois does not have one appeal deadline. Each township publishes its assessment list on its own schedule, and the filing window with the Board of Review is 30 days from that township's publication date, not from a fixed date on the calendar. In practice, publication dates cluster in the summer and fall depending on the county and the reassessment cycle, but there is no single day every Illinois homeowner can circle. Watch your mail and your township assessor's office directly; by the time you see a general news story about "assessment season," your own township's 30 days may already be running.

Once the Board of Review rules, if you want to go further you have 30 days from the postmark of that written decision to file with the Property Tax Appeal Board (PTAB), a separate deadline from the original township one and easy to confuse with it. Beyond PTAB, Illinois also allows a Circuit Court tax objection route, typically reserved for higher-value disputes where litigation costs make sense.

What RESPA Makes Your Servicer Do With the Savings

Once the corrected bill finally reaches your servicer, three federal rules in 12 CFR 1024.17 govern what happens to the difference. These are the same rules in every state; the CFPB enforces all of them.

• The surplus rule. If an escrow analysis shows a surplus of $50 or more, the servicer must refund it within 30 days of that analysis (1024.17(f)(2)(i)), as long as you are current on the loan (f)(2)(ii). Below $50, they may credit it forward instead.
• The cushion cap. A servicer may hold a cushion of no more than one-sixth of estimated annual disbursements, roughly two months' worth (1024.17(c)(5)). When your corrected bill lowers the projected annual total, the maximum allowed cushion shrinks too, which is why a post-appeal refund is often larger than the tax savings alone.
• The annual statement. Within 30 days of the computation year's end, you get a statement listing every disbursement (1024.17(i)). After a Board of Review year, check it against the actual bill the county sent; confirm your servicer paid the corrected amount, not the pre-appeal figure.

Pulling the Savings Forward

Regulation X lets, but does not require, a servicer to run an escrow analysis at other times during the computation year (1024.17(f)(1)(ii)). Because Illinois's arrears billing already builds in a year of delay before the corrected bill even exists, this is the one lever worth pulling hard: as soon as the county actually mails the corrected bill (not when the Board of Review issues its decision, since there is nothing for the servicer to act on yet), send the escrow department the Board of Review or PTAB order and the corrected bill together, and ask in writing for an off-cycle re-analysis. Many servicers will do it, because an accurate projection is in their interest too. If yours declines, the annual analysis will still catch it, and the surplus rule guarantees the overage eventually comes back.

The Cook County Wrinkle

Cook County adds two more layers most of the rest of the state does not have. First, its Classification Ordinance assesses Class 2 residential property at 10% of fair market value, not the statewide 33.33% (35 ILCS 200/9-145 sets the general rule; Cook's ordinance is the carve-out). That means the assessed-value figure on a Cook County notice looks much smaller than a downstate figure for the same market value home, purely because of the ratio, not because the taxing rate is lower. Do not compare raw assessed-value numbers across county lines; compare the market values behind them.

Second, Cook County splits its arrears billing into two installments, and the first one has nothing to do with your current appeal. By statute, the first installment is set at 55% of the prior year's total tax bill, before any current-year assessment change, appeal result, or exemption is applied. If you win at the Board of Review this year, that win will not appear until the second installment, which is the one that actually recalculates against the new assessment. A Cook County homeowner who sees an unchanged first-installment bill after a successful appeal has not lost the appeal; the correction simply has not reached that particular bill yet.

Where to File, and What Each Level Actually Does

Illinois gives you four levels, and you generally work through them in order:

1. County Assessor (Informal). A conversation with the assessor's staff, often the fastest way to fix a straightforward data error, like wrong square footage.
2. Board of Review. Your county-level appeal, filed within 30 days of your township's publication date. An oral hearing is optional, not required; you can submit comparable sales and documentation in writing and let the Board decide on the record if you prefer not to appear.
3. Property Tax Appeal Board (PTAB). A state-level administrative review, available once the Board of Review has ruled, with its own 30-day filing deadline running from the postmark of that decision. Online filing is available at both the Board of Review and PTAB stages in most counties.
4. Circuit Court. Formal litigation, typically reserved for higher-value or higher-stakes disputes.

Your lender has no role at any of these four levels. It is not notified, it does not need to consent, and it cannot file on your behalf. It only enters the picture once the county issues a corrected bill for your servicer to pay.

Notable High-Volume Counties

Cook, DuPage, and Lake are three of the most populous counties in Illinois, and the ones where the mechanics above matter to the most homeowners. Cook runs the triennial cycle and the 10% ratio described above; DuPage and Lake are both downstate-rule counties on the quadrennial cycle at the statewide 33.33% ratio, though each sets its own local publication schedule and Board of Review procedures within that framework. Always confirm your specific township's publication date directly; a countywide reassessment year does not mean every township publishes on the same day.

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