Rob Hartley

Founder, AppealDesk · February 13, 2026

Property Tax Assessment Ratios by State: Complete 2026 Guide

Updated February 2026 · 12 min read

What Is a Property Tax Assessment Ratio?

A property tax assessment ratio (also called an assessment level, assessment percentage, or level of assessment) is the percentage of a property's fair market value that a taxing jurisdiction uses as the taxable base. The International Association of Assessing Officers (IAAO) publishes standards governing how these ratios should be applied and measured. Every state sets its own ratio by statute, and it determines how your assessed value relates to what your property is actually worth.

Here's the fundamental formula:

For example, if your home has a fair market value of $400,000 and you live in a state with a 25% assessment ratio, your assessed value would be $100,000. Your property taxes are then calculated on that $100,000 base — not on the full $400,000.

Why Do States Use Fractional Assessment Ratios?

Fractional assessment is largely a historical artifact. In earlier eras, state legislatures adopted lower ratios to make the numbers on tax bills appear smaller — even though tax rates (millage rates) were adjusted upward to compensate. The net tax paid is the same whether your state assesses at 10% with a high millage rate or at 100% with a low millage rate. The critical distinction is transparency: 100% assessment states make it easier for homeowners to compare their assessed value to comparable sales, while fractional states add an extra layer of math that confuses many people.

How Assessment Ratios Create Confusion During Appeals

This confusion is where the biggest overassessment mistakes happen. In a fractional assessment state, your assessed value is intentionally lower than your home's market value — that's by design, not because the county is giving you a break. If you compare your assessed value directly to sale prices without accounting for the ratio, you'll reach the wrong conclusion about whether you're overassessed.

To properly evaluate your assessment, you must convert your assessed value back to an implied market value using the formula above, then compare that implied market value to comparable sales. This is the single most important concept in property tax appeals for homeowners in fractional assessment states.

Assessment Ratios by State: Complete 2026 Table

The table below lists the statutory assessment ratio for every U.S. state plus the District of Columbia, along with the statutory source, median home value, and effective tax rate. States that assess at 100% of market value are marked with a 100% badge. States with fractional ratios are marked with an amber badge showing their ratio.

Sources: State statutes (cited in Statutory Source column), U.S. Census Bureau ACS median home values (2024–2025 vintage), Tax Foundation and Census Bureau effective rate estimates. Ratios shown are for residential (owner-occupied) property; some states use different ratios for commercial, industrial, or agricultural property.

Why Assessment Ratios Matter for Property Tax Appeals

If you're preparing to appeal your property taxes, understanding your state's assessment ratio is not optional — it's the foundation of your entire case. Here's why:

The #1 DIY Appeal Mistake

The most common mistake homeowners make when appealing on their own is comparing their assessed value directly to comparable sale prices in a state that does not assess at 100%. This error leads to one of two outcomes: either you think you're not overassessed when you actually are (because your assessed value looks “low” compared to sale prices), or you present a fundamentally flawed argument to the appeals board that undermines your credibility.

In either case, the fix is simple: always convert your assessed value to an implied market value before comparing to comparable sales. Let's walk through some real-world examples.

Worked Example: Tennessee (25% Assessment Ratio)

Worked Example: South Carolina (4% Assessment Ratio)

Worked Example: New York (Variable Ratios by Municipality)

States with Unusual Assessment Systems

While most states use a straightforward percentage of market value, several states have assessment systems with important wrinkles that homeowners should understand before filing an appeal.

California: Proposition 13 (Acquisition Value System)

California nominally assesses at 100% of market value, but Proposition 13 (passed in 1978) fundamentally changes how that value is determined. Instead of reassessing to current market value each year, California sets your base year value at the purchase price and limits annual increases to 2% — regardless of how much the market has appreciated.

This means a home purchased in 2000 for $300,000 might have a 2026 assessed value of approximately $500,000 (after 26 years of 2% annual increases), even if its current market value is $1,200,000. The effective assessment ratio for that homeowner is closer to 42% of current market value, even though the state officially assesses at “100%.”

For California appeals, the relevant question is not whether your home is assessed above your purchase price plus 2% annual growth — it's whether your home's current assessed value exceeds its current market value. If property values have declined since your purchase (or since a recent reassessment event), you may have grounds for a Proposition 8 temporary reduction. See the California appeals guide for details. For a deeper dive into Prop 13 mechanics, Prop 8 decline-in-value claims, and Prop 19 base year transfers, see our California Prop 13 appeal guide.

New York: Level of Assessment Varies by Municipality

As mentioned in the worked example above, New York does not have a single statewide assessment ratio. Each city, town, or village sets its own Level of Assessment (LOA), which can range from under 1% to 100%. The NYS Office of Real Property Tax Services publishes equalization rates annually that indicate the ratio of total assessed value to total market value for each municipality.

When appealing in New York, you must use your specific municipality's equalization rate — not a statewide number. Two homes with identical market values in adjacent towns can have vastly different assessed values, and both can be correctly assessed. The process is called “grieving” your assessment, and deadlines vary by jurisdiction.

Illinois: Classification-Based Ratios (Cook County)

Illinois uses a 33.33% assessment ratio statewide, but Cook County (Chicago) applies a classification system with different ratios for different property types. Residential property in Cook County is assessed at 10% of market value, while commercial and industrial properties are assessed at 25%. This means the same building could have dramatically different assessed values depending on its classification.

If you live in Cook County, use the 10% residential ratio when analyzing your assessment, not the 33.33% statewide figure. Outside Cook County, the standard 33.33% ratio applies to residential property.

West Virginia: 60% Ratio with Inconsistent Application

West Virginia's constitution requires property to be assessed at 60% of fair market value. However, the actual application of this ratio has historically been inconsistent across the state's 55 counties. Some counties maintain assessments closer to 60% of current market value, while others may lag significantly behind, creating effective ratios well below the statutory 60%.

For West Virginia appeals, compare your assessed value to 60% of your evidence of market value. If your assessed value exceeds 60% of what comparable sales indicate your home is worth, you have a strong case for reduction.

Minnesota: Limited Market Value Phase-In

Minnesota assesses at 100% of market value but applies a “limited market value” provision that caps how quickly your assessed value can increase in a single year. This means rapidly appreciating properties may be temporarily assessed below full market value as the assessment catches up over multiple years. Once the limited market value equals actual market value, the standard 100% ratio applies fully.

100% Assessment States vs. Fractional Assessment States

From an appeal standpoint, the distinction between 100% assessment states and fractional assessment states is one of complexity, not tax burden. A state's assessment ratio does not determine how much you pay in property taxes — the effective tax rate does.

Advantages of 100% Assessment States (for Homeowners)

• Direct comparison: Your assessed value equals what the county thinks your home is worth. If your assessment says $400,000, you just need to prove your home is worth less than $400,000.
• Simpler evidence presentation: You can present comparable sales data directly without conversion math.
• Less room for error: No risk of comparing assessed value to sale prices without adjustment.
• Easier for hearing boards: Board members can follow your argument without ratio calculations.

Texas is the largest 100% assessment state and has its own unique protest process. See our Texas property tax protest guide for state-specific details including Form 50-132, ARB hearings, and county-by-county filing information.

Challenges of Fractional Assessment States

• Extra math required: You must convert assessed values to implied market values before any comparison.
• Confusion risk: Many homeowners (and some newer board members) conflate assessed value with market value.
• Small numbers mislead: In South Carolina (4%), a home worth $300,000 is assessed at $12,000 — a number that feels “low” and discourages appeals.
• Different ratios for property types: Some fractional states (like Illinois) apply different ratios to residential vs. commercial property, adding another layer of complexity.

How to Use Your Assessment Ratio in a Property Tax Appeal

Whether you live in a 100% state or a 4% state, the appeal process follows the same logical steps. Here's the framework, with the assessment ratio built in at every stage.

If this process feels overwhelming, you're not alone. AppealDesk’s $49 flat-fee property tax appeal evidence packets handle the ratio calculations, comparable sales research, and evidence generation automatically for all 50 states — so you get a professionally prepared appeal without doing the math yourself.

Assessment Ratios by Region: What to Know

Southern States: Wide Range of Ratios

The South has the widest variety of assessment ratios in the country. South Carolina sits at the extreme low end with a 4% residential ratio, while Florida and Georgia assess at 100% and 40% respectively. Alabama uses a 10% ratio, Mississippi uses 10–15% (depending on property class), and Tennessee uses 25% for residential property. These low ratios make the conversion to implied market value especially important for Southern homeowners preparing appeals.

Northeast: Complex Systems, High Stakes

Northeastern states tend to have higher effective tax rates, which means assessment errors cost more in real dollars. New Jersey, Connecticut, and New Hampshire all assess at 100%, making the appeal math straightforward but the stakes high. New York's variable municipal ratios add complexity, and Pennsylvania has some of the most outdated assessments in the country, with some counties using base year values from decades ago.

Midwest: Moderate Ratios, High Tax Rates

Many Midwestern states use fractional ratios in the 15–35% range. Ohio uses 35%, Indiana uses approximately 100% (with deductions rather than fractional assessment), and Illinois uses 33.33% (with Cook County's 10% exception). Combined with relatively high tax rates, Midwestern homeowners often have the most to gain from appeals but must be careful with ratio conversions.

West: Mostly 100% Assessment States

Western states predominantly assess at 100% of market value, including California, Oregon, Washington, Idaho, Montana, and Arizona. The main exception is Colorado, which uses a residential ratio that is adjusted periodically (currently around 6.7%). California's Proposition 13 system makes it an outlier even among 100% states, as explained above. For most Western homeowners, the appeal process is more straightforward because assessed value directly reflects the county's market value opinion.

Assessment Ratio vs. Effective Tax Rate: Don't Confuse Them

Homeowners often confuse the assessment ratio with the effective tax rate. They measure different things:

Consider this comparison: Alabama has a 10% assessment ratio and a 0.4% effective tax rate. California has a 100% assessment ratio but (approximately) a 0.71% effective tax rate. Alabama's assessed values look lower on paper, but Californians actually pay a more similar effective rate than the 10x difference in assessment ratios would suggest. The tax rate (millage) compensates for the assessment ratio.

When evaluating whether to appeal, focus on whether your implied market value exceeds what your property would actually sell for — not on whether your assessment ratio seems “high” or “low.” Every dollar of overassessment costs you real money, regardless of the ratio used to calculate it.

Frequently Asked Questions

Now that you understand your state's assessment ratio, use our savings calculator to check if your assessment is too high, then follow our appeal checklist to prepare your case.

Data sources: Individual state statutes (cited in table), U.S. Census Bureau American Community Survey (median home values, 2024–2025 vintage), Tax Foundation (effective tax rate estimates), IAAO Standard on Ratio Studies, Lincoln Institute of Land Policy Significant Features database. Assessment ratios shown are for residential owner-occupied property. Some states apply different ratios to commercial, industrial, agricultural, or personal property. Last verified February 2026.