56% of Riverside homes that appealed won in 2023 — and the 2026 deadline was June 8.

If you live in Riverside Township and you're holding a 2026 reassessment notice — or wondering whether the appeal that landed in your mailbox in late April is worth filing in the next window — this is the data analysis you need. We pulled every Riverside appeal record from 2023 through 2025 using verified Cook County public records and ran the math. The short version: filing works more often than most homeowners assume, particularly in reassessment years like 2026, and particularly when you file at both the Cook County Assessor and the Board of Review. The longer version, with breakdowns by year, tier, and property class, follows.

01 · The headline dataHow often do Riverside property tax appeals actually win?

Cook County's property tax appeal system has three tiers — the Cook County Assessor (CCAO), the Cook County Board of Review (BOR), and the Illinois Property Tax Appeal Board (PTAB). Each is an independent review with its own standards and its own success rate. The data shows substantial variation across all three.

The 2023 Riverside numbers (the most recent reassessment year)

The 2023 reassessment is the most relevant year for the 2026 cycle, because reassessments follow the same three-year rotation. Here's how Riverside performed that year:[1][2]

Two things stand out immediately. First, the Board of Review approves a substantially higher share of appeals than the Assessor — 54.9% vs. 34.1% of homeowner appeals in 2023. That gap is consistent across years and across townships, and it reflects how the two agencies are structured: the Assessor reviews valuations its own office set, while the Board of Review is a separate three-member elected body that reviews evidence from scratch. Second, counting each appeal once (a condo building's units, decided together, are one appeal), the rate at either tier alone tells only part of the story — the share of homes that won somewhere is the more interesting statistic.

Homes that won anywhere — by year

The per-tier rates above (34.1% at the Assessor, 54.9% at the Board) measure outcomes for individual appeals. But most Cook County property owners care about a different question: "If I appeal, what's the probability I'll get a reduction somewhere?" For that question, the right measurement is what we call the won-anywhere rate — the share of Riverside homes that filed any appeal in a given tax year and received at least one reduction at any tier that year. It counts homes, not appeals: each home once, whether it appealed at one tier or both.

The pattern is the most important takeaway from this analysis. Reassessment years produce materially higher success rates than non-reassessment years — 56.2% in 2023 versus 48.0% in 2024 and 40.6% in 2025. Two factors drive the gap. First, reassessment years bring in higher appeal volume from owners reacting to new valuation notices, which includes more strong cases. Second, the Cook County Assessor has more discretion to correct values in the year they're being set; in later years, the Assessor's office is more constrained by precedent.[3]

The implication for 2026: the next Riverside reassessment year is the strategic year to file. Properties planning to appeal should anchor their expectations on the 2023 number (56.2%), not the non-reassessment-year rates that follow it.

02 · The three-tier strategyWhy filing at both CCAO and BOR is the winning move

Most homeowners file a Cook County property tax appeal once, at the Cook County Assessor, and stop if they get a "no change" decision. The data shows that's the wrong move. The Board of Review is an entirely separate appeal with its own filing window — and the data shows it approves substantially more reductions than the Assessor.

How the three tiers differ

• Cook County Assessor (CCAO). Reviewed by the office that set your value. In Riverside Township, the 2026 appeal window opened April 24 (when reassessment notices mailed) and closed June 8, 2026. Approves about a third of residential appeals during reassessment years.
• Cook County Board of Review (BOR). An independent three-member elected body. The BOR window for Riverside opens after the Assessor certifies its results — typically late summer or fall. Approved more than half of Riverside homeowner appeals in the 2023 reassessment year (54.9%).[2]
• Illinois Property Tax Appeal Board (PTAB). A state-level review of last resort. Decisions take 12–30 months; mostly used for high-stakes commercial cases or properties where CCAO and BOR both declined despite strong evidence.

The decomposition by year shows exactly how the two-tier strategy pays off — and it shows the pattern is consistent every year, not just in reassessment years. For each Riverside tax year, here is how the appellant pool divides:

The full year-by-year decomposition:

• 2023 (reassessment year): 460 won only at CCAO · 855 won only at BOR · 197 won at both · 1,179 lost at every tier. 1,512 homes (56.2%) ended with at least one reduction.
• 2024: 116 won only at CCAO · 665 won only at BOR · 28 won at both · 877 lost at every tier. 809 homes (48.0%) ended with at least one reduction.
• 2025: 156 won only at CCAO · 392 won only at BOR · 20 won at both · 830 lost at every tier. 568 homes (40.6%) ended with at least one reduction.

The headline finding is consistent across all three years: "won only at BOR" is the largest winning segment, every year. In 2023, the only-BOR group was nearly 2x larger than the only-CCAO group. In 2024, it was nearly 6x larger. In 2025, it was 2.5x larger. Across the three years combined, 1,912 Riverside homes won reductions only at the Board of Review — they would have ended with no reduction if they'd stopped at CCAO. That is the single most important data point for any property owner deciding whether to file at one tier or both.

Why so many properties never benefit from these rates

The won-anywhere rates apply only to homes that appeal. Riverside has 6,466 parcels in total, 5,902 of them homes. In each of the three years analyzed, only a fraction filed at any tier — 2,691 homes in 2023, 1,686 in 2024, 1,398 in 2025. The majority of the township's homes pay tax based on the Assessor's initial value with no challenge. The strategic question every year is whether to be in the appellant pool or outside it.

03 · By property classWho wins more often: residential, commercial, or condo?

The 34.1% Assessor figure for 2023 Riverside is the homeowner number. Commercial and condo appeals had materially different outcomes that same year:

Why commercial wins more often

Two reasons. First, commercial valuations rely on income-approach methodology (capitalization rate, net operating income), which produces clearer "wrong value" arguments than the sales-comparison approach used for residential properties. Second, commercial appeals are almost always filed by attorneys or licensed agents with deep property-tax experience, who self-select into the cases most likely to win. Residential appeals include far more pro se filings with marginal evidence, which pulls the average rate down.

04 · Dollar valueWhat a typical Riverside reduction actually saves

A reduction in assessed value is not the same as a reduction in your tax bill — the bill depends on the equalization factor and local tax rate. Here's how the math actually translates:

The full conversion: $4,961 in AV reduction × the 2023 Illinois equalization factor of 3.0163 = $14,964 in equalized assessed value, multiplied by Riverside's effective tax rate of approximately 9.3% = $1,392 per year in real tax savings. Across the three-year reassessment cycle (2026, 2027, 2028 bills), that adds up to roughly $4,175 in total tax savings on the average case, at today's tax rate.

For commercial properties the dollar figures are larger by an order of magnitude. The average winning commercial appeal in 2023 Riverside reduced assessed value by $107,237 — translating to roughly $30,100 a year in tax savings, or $90,200 over the reassessment cycle. The higher the underlying property value, the larger the absolute dollar reduction tends to be.

05 · Using this dataWhat the success rates mean for 2026

Three concrete actions, ranked by impact, if you're a Riverside property owner planning the next appeal:

1. File at both the Cook County Assessor AND the Board of Review. The Riverside data is unambiguous on this. In 2023, 855 homes — the largest single winning segment — won reductions only at the Board of Review after losing or not filing at CCAO. Stopping at the Assessor's stage is the single most common preventable mistake. The 2026 CCAO window closed June 8 and the BOR window ran August 3 to September 1. File at both next time.
2. If your 2023 appeal didn't win, refile in 2026. The 2026 reassessment establishes a fresh estimated market value with fresh evidence and fresh comparable sales. A prior "no change" decision has zero binding effect. Reassessment years also produce materially higher success rates than non-reassessment years — 56.2% of homes that appealed won somewhere in 2023, versus 48.0% in 2024 and 40.6% in 2025. 2026 is the strategic year to refile.
3. Build evidence-quality before you file. For residential properties, the strongest single piece of evidence is 3 to 5 comparable sales of similar homes within 0.5 miles, sold 2023 to 2025, where the per-square-foot price is materially below your assessment implies. Documented factual errors (wrong square footage, wrong bath count) come second — and they're the easiest appeals to win.

The 2026 Riverside windows

The Cook County Assessor mailed 2026 reassessment notices to Riverside Township homeowners on April 24, 2026. The appeal deadline at the Assessor's Office was 11:59 PM on June 8, 2026, and the Board of Review's Riverside window ran August 3 to September 1, 2026. For a detailed walkthrough of the 2026 Riverside reassessment process, see our companion guide: Riverside Property Tax Appeal 2026: Deadline June 8.

Frequently asked questions about Riverside appeal success rates

The Riverside data is clear: appeals work — especially when you file strategically.

The single most important takeaway from this analysis: filing once at the Cook County Assessor and stopping at "no change" leaves substantial probability on the table. In every year analyzed (2023, 2024, 2025), the largest winning segment was homes that won only at the Board of Review — 855 in 2023, 665 in 2024, 392 in 2025. They would have walked away with nothing if they'd stopped at CCAO. For the next Riverside window, the strategic move is to file at the Assessor and to plan for a Board of Review filing in the late-summer window that follows.

Cook County Tax Appeals handles every stage of the process. Our licensed Illinois tax attorneys and CPAs build the evidence, file the petitions, and escalate strategically across tiers wherever it produces the largest reduction. We charge 25% of first-year savings, only if your assessment is reduced. There is no upfront cost.