What is the assessment ratio in my state?

Last updated 2026-07-10

What is an assessment ratio and why does it exist?

The assessment ratio is the fraction of a property's full market value that a jurisdiction actually taxes. Some states call it the assessment level or assessment percentage. If your state uses a 50% ratio and your home is worth $400,000, the taxable assessed value is $200,000. The mill rate applies to that $200,000, not the full $400,000.

States set ratios below 100% for old reasons. Some legislatures wanted a cushion against fast market appreciation, so homeowners would not get hit with sudden tax spikes. Others set different ratios by property class, taxing commercial real estate at a higher fraction than homes. And a few states simply kept a fraction from the era when assessment technology was rough, then never bothered to update it.

Here is the part most homeowners get wrong. The ratio does not lower your taxes in any real way. A jurisdiction with a 30% ratio tends to run mill rates roughly three times higher than a comparable one at 100%. The math cancels.

What the ratio does change is your appeal. Your assessor is legally required to assess you at the correct fraction of market value, not at some number that feels about right. Say the ratio is 50% and your assessed value implies a $500,000 home, but you can prove yours is worth $420,000. You have a winning appeal, and it has nothing to do with what your neighbor pays.

What assessment ratios do states actually use?

The table below shows the statutory or target residential assessment ratio for every state, drawn from the Lincoln Institute of Land Policy's 50-State Property Tax Comparison (2023) and individual state statutes. Some states set a range instead of a fixed figure. Others set ratios by property class. Where a state mandates 100%, the assessed value is supposed to equal full market value, though equalization studies often show a lower de facto ratio in practice.

State	Statutory Residential Ratio	Notes
Alabama	10%	Const. Art. XI, §217 [1]
Alaska	100%	Varies by borough
Arizona	10%	A.R.S. §42-15002 [2]
Arkansas	20%	Const. Art. 16, §5
California	100%	Prop 13 limits increases to 2%/yr [3]
Colorado	6.765% (2023)	Residential only; HB23-1311
Connecticut	70%	CGS §12-64
Delaware	Varies by county	New Castle ~100%
Florida	100%	Save Our Homes caps increases
Georgia	40%	O.C.G.A. §48-5-7 [4]
Hawaii	100%	Varies by county class
Idaho	100%	IC §63-205
Illinois	33.33% (Cook: 10%)	35 ILCS 200/9-145 [5]
Indiana	100%	IC §6-1.1-4-39
Iowa	varies	Residential ~54.65% (2023 rollback)
Kansas	11.5% residential	KSA §79-1439
Kentucky	100%	KRS §132.191
Louisiana	10%	La. Const. Art. VII §18
Maine	100%	36 M.R.S. §701
Maryland	100%	Phased 3-yr increases
Massachusetts	100%	MGL Ch. 59 §38
Michigan	50%	MCL §211.27a
Minnesota	100% (class-based credits)	Minn. Stat. §273.11
Mississippi	10% residential	Miss. Code §27-35-4
Missouri	19% residential	Mo. Const. Art. X §4(b)
Montana	100%	Market value standard
Nebraska	100%	Neb. Rev. Stat. §77-112
Nevada	35%	NRS §361.225
New Hampshire	100%	RSA 75:1
New Jersey	100% (county equalization)	Varies widely in practice
New Mexico	33.33%	NMSA §7-36-15
New York	Varies by class/county	NYC Class 1: ~6% [6]
North Carolina	100%	GS §105-283
North Dakota	50%	NDCC §57-02-27
Ohio	35%	ORC §5715.01
Oklahoma	11%	68 O.S. §2817
Oregon	100% (capped MAV)	Measure 50 (1997)
Pennsylvania	Varies by county	Many use 100%
Rhode Island	100%	RIGL §44-5-15
South Carolina	4% owner-occupied	SC Code §12-43-220
South Dakota	85%	SDCL §10-6-33
Tennessee	25% residential	TCA §67-5-602
Texas	100%	Tax Code §23.01
Utah	100%	UCA §59-2-103
Vermont	Listed value	Education grand list
Virginia	100%	Code of VA §58.1-3201
Washington	100%	RCW §84.40.030
West Virginia	60%	WV Code §11-3-1
Wisconsin	100%	Wis. Stat. §70.32
Wyoming	9.5% residential	WY Stat. §39-13-103

These are statutory targets. The ratio your county actually hits is measured by a sales ratio study, which compares recent sale prices against assessed values. In many states the real-world ratio drifts below the statutory floor. That gap is exactly where over-assessments hide. ^[7]

How does the assessment ratio change my actual tax bill?

Your tax bill is Assessed Value times Mill Rate. The assessed value is Market Value times Assessment Ratio. Put those together and the full formula is:

Tax = Market Value × Assessment Ratio × Mill Rate

Two states can tax a $300,000 home at an effective 1% rate. Both homeowners pay $3,000. One state gets there with a 10% ratio and a 100-mill rate. The other uses a 100% ratio and a 10-mill rate. Same bill. The ratio and the mill rate are counterweights, and they push in opposite directions on purpose.

What you actually care about is whether your assessment is accurate relative to the ratio. Here is the test. Take your assessed value, divide it by your state's ratio, and ask whether that number is what your home would sell for today. Say your assessed value is $180,000 and your ratio is 40%. The implied market value is $450,000. If comparable homes in your neighborhood are selling for $370,000, the assessor is taxing you as if your home is worth $80,000 more than it is.

For high-volume counties, see how this math runs in practice in our piece on the cook county tax assessor tax bill, or the la county property tax breakdown.

What is an equalization ratio and how is it different?

The equalization ratio is the measured relationship between current assessed values and actual sale prices in your jurisdiction. Depending on the state it goes by common level ratio, assessment-to-sales ratio, or equalization rate. A state agency calculates it, not your local assessor. That independence is the whole point.

Here is why it matters for your appeal. Suppose your state's statutory ratio is 100%, but the equalization study finds the county is assessing at 85% of market value. The effective target for any single property becomes 85%, not 100%. Boards of equalization and tax courts routinely swap in the equalization ratio when they run the appeal math. In New Jersey, the county-wide Common Level Ratio is published every year by the Division of Taxation and is the standard actually used in appeals under N.J.S.A. 54:4-23. ^[8]

So if your county's equalization ratio is 85% and your implied market value (assessed value divided by 0.85) is higher than what your home would sell for, you probably have a strong case. Some states require assessors to stay inside a corridor around the equalization ratio, often within 15 percentage points of the common level.

Maryland runs its own version of this through a three-year phased assessment system. The montgomery county property tax article walks through how that works.

Which states have different ratios for different property types?

Many states run a classified property tax system, where commercial, agricultural, industrial, and residential properties each carry a different assessment ratio. The intent is to shift the tax burden toward certain classes, usually commercial and industrial, and away from homeowners. Sometimes it works. Often it just creates confusion in appeals.

Illinois is the sharpest example. Outside Cook County, the statutory ratio is 33.33% for most property. Inside Cook County, homes are assessed at 10% of market value while commercial properties sit at 25%. ^[5] That is a large wealth transfer from commercial owners to residential owners, and it helps explain why Chicago's commercial property tax burden ranks among the highest in the country in Lincoln Institute of Land Policy data. ^[7]

New York City uses four classes with sharply different ratios. Class 1 (one-to-three family homes) is capped by statute at roughly 6% of market value. Class 4 (commercial) targets 45%. ^[6] The gap is deliberate policy. It also complicates appeals, because you compare your property to others in the same class, never across classes.

Minnesota takes a different route. It assesses most property at 100% of market value, then applies a class rate multiplier before the mill rate, which produces the same math as a different ratio. Agricultural homestead property carries a 0.5% class rate on the first $500,000 of market value. Commercial-industrial property runs at 1.5%. ^[9]

Georgia assesses all real property at 40% ^[4], but the homestead exemption then removes a flat dollar amount from that assessed value. Two homeowners in the same county can end up with very different effective ratios. The gwinnett county tax assessor and bibb county tax assessor articles show how this lands in two very different Georgia markets.

How do I find my county's actual assessment ratio?

Four places to look, in rough order of reliability.

Start with your state department of revenue or tax commission. It publishes an annual equalization report or sales ratio study. Search your state name plus "equalization rate" or "assessment-to-sales ratio study." These are usually PDFs on state government sites. The Iowa Department of Revenue publishes rollback fractions each year that work as equalization adjustments. The New York State Office of Real Property Tax Services publishes equalization rates for every municipality annually.

Next, check your county assessor's website. The ratio is often stated directly in a FAQ or in the notes that come with your assessment notice. If it isn't, call and ask: "What is the common level ratio for residential property in this county for the current assessment year?" They have to tell you.

Third, read your assessment notice. It sometimes lists both the market value estimate and the assessed value. Divide assessed by market, and there's your implied ratio. If the two numbers match, your jurisdiction uses 100%.

Fourth, the Lincoln Institute of Land Policy publishes its 50-State Property Tax Comparison every year with median assessment-to-market ratios by state and property class. ^[7] It isn't county-specific, but it gives you a benchmark to sanity-check whatever your county reports.

Texas works differently because of its statutory 100% standard. The Texas Comptroller runs a Property Value Study every two years that measures assessment accuracy by school district. If a district assesses below 95% of market value, state aid gets adjusted. That outside pressure keeps Texas ratios reasonably honest, though individual property errors still happen constantly, as the bexar county tax assessor article shows.

How does the assessment ratio affect whether my appeal will succeed?

The ratio is not trivia. It sets what your assessed value is supposed to represent, and therefore what evidence you need to win.

In a 100% state, your assessed value should match market value. Your job is to show comparable sales prove a lower number. Simple.

In a fractional-ratio state, add a step. If your state's ratio is 40% and your assessed value is $160,000, the assessor is claiming your home is worth $400,000. Your evidence (recent comparable sales, an appraisal) has to show the real market value is below $400,000, not that $160,000 looks high on its own.

Some appeal boards convert all evidence to the same ratio before comparing. Others want you to present market value evidence and then apply the ratio themselves. Find out which procedure your state uses before your hearing. The instructions on your state's appeal petition form usually spell it out.

One argument genuinely helps. Say a sales ratio study shows your county assessing at 92% of market value, but your property sits at 110%. You are assessed 18 percentage points above the county norm. That selective over-assessment is independently appealable in most states under the uniformity clause of the state constitution, separate from any market value fight. The principle comes from the U.S. Supreme Court in Allegheny Pittsburgh Coal Co. v. County Commission (1989), which held that grossly disparate assessments within a jurisdiction violate the Equal Protection Clause. ^[10]

You can build this yourself without a contingency firm. The TaxFightBack DIY appeal kit walks through pulling sales ratio data and constructing a uniformity argument from public records.

What happens when the assessment ratio is applied unevenly across a neighborhood?

This is one of the best-documented forms of assessment inequity in American property taxation. A 2021 analysis by the University of Chicago's Harris School and ProPublica found that in many jurisdictions, lower-value homes are assessed at effective ratios systematically higher than higher-value homes in the same county, even where the statutory ratio is uniform. ^[11] The work drew on assessment data from Cook County, Illinois and several other large counties.

Put it plainly. Suppose the county's equalization ratio is 33%, but homes in your zip code are assessed at 38% of market value while a wealthier zip code sits at 28%. The wealthier owners are getting a tax break the law does not authorize. This is not a fringe complaint. The International Association of Assessing Officers admits that hitting uniform assessment ratios across property value tiers is one of the hardest technical problems in mass appraisal. ^[12]

If you think this is happening near you, the strongest evidence is a regression of assessment-to-sale ratios for recent comparable sales in your neighborhood against the county average. Some appeal boards accept that statistical evidence directly. Others want a licensed appraiser to present it. Either way, it starts with pulling public sales data, which is free in most counties through the assessor's or recorder's office.

Minnesota uses its annual sales ratio study to keep assessors honest. The hennepin county property tax article shows that model, worth knowing if you live in a state with weaker oversight.

Does a low assessment ratio protect me from over-assessment?

No. This is a common misread. A 10% ratio in Alabama or Louisiana does not mean homeowners there pay less or catch fewer errors. It just means the assessed value is a smaller number. The mill rate is higher to make up for it. An error in the market value estimate still flows through the ratio and inflates your bill by the same percentage it would in a 100% state.

If your home is worth $200,000 but the assessor's market value estimate is $240,000, you are over-assessed by 20%, whether the ratio is 10% or 100%. Your tax bill is 20% too high either way. The ratio is neutral on this.

What a fractional ratio changes is the size of the absolute dollar error, and that is what fools people. A 20% over-assessment on a $200,000 home means a $40,000 error in market value. At a 10% ratio, your assessed value is inflated by $4,000 (from $20,000 to $24,000). At a 100% ratio, it is inflated by $40,000. The mill rate adjusts so both owners pay the same extra dollars, but the small number lulls people into ignoring it.

New York City is where this gets truly slippery. Class 1 homes carry a ratio near 6%. An assessed value of $50,000 on an $800,000 brownstone looks fine at a glance. But run the math: $50,000 divided by 0.06 implies a market value of $833,333. If the property would sell for less, the owner is over-assessed. The nyc property tax article shows how to do this for all four NYC classes.

How do I use my state's assessment ratio to calculate my fair assessed value?

Two steps.

Step 1: Estimate your home's actual market value. The most reliable method is recent sale prices of comparable homes: same neighborhood, similar size, condition, and age, sold in the past six to twelve months. Pull them from your county assessor's public records or a real estate data site. If the comps line up, average them. If you want a formal opinion, a licensed appraiser charges $300 to $600 for a residential appraisal, but for a board of review hearing, comparable sales evidence is often enough on its own.

Step 2: Multiply your market value estimate by your jurisdiction's assessment ratio. That gives the assessed value you should have. If you believe your home is worth $350,000 and your state uses a 40% ratio, your target assessed value is $140,000. If your current assessed value is $172,000, that is a $32,000 over-assessment and a reasonable appeal.

Use the equalization ratio if your state publishes one that differs from the statutory ratio. In New Jersey, the published Common Level Ratio for your municipality is the number that matters, not the statutory 100%. ^[8]

States with capped assessed values (California under Prop 13, Oregon under Measure 50) work differently. The assessed value cannot exceed market value but can sit far below it. The ratio concept applies at initial assessment and when a property changes ownership, but not during the years when the cap is actively holding the value below market. ^[3]

Where can I find the actual statute or rule that sets my state's ratio?

Statutory ratios live in state law, usually in the property tax chapter of the state code. Here are starting points for several major states, plus a research method for the rest.

For any state, search: [state name] + "assessment ratio" + "state statute" OR "state code". The result should be either the legislature's official code site or the department of revenue's property tax guidance. Both are primary sources.

Key pages:

• Georgia: O.C.G.A. §48-5-7 through the Georgia General Assembly website. 40% ratio for all real property. ^[4]
• Illinois: 35 ILCS 200/9-145 for the one-third ratio; Cook County's 10% residential ratio is at 35 ILCS 200/9-150. ^[5]
• Arizona: A.R.S. §42-15002 for the 10% residential ratio. ^[2]
• California: Revenue & Taxation Code establishes the 100% full value standard; Article XIIIA of the California Constitution (Prop 13) limits annual increases to 2% or the CPI rate, whichever is lower. ^[3]
• New Jersey: The Division of Taxation publishes the Common Level Ratio table each year. ^[8]

Commercial property rules can differ a lot from residential in a major market. The santa clara property tax article covers how California's change-in-ownership rules trigger reassessment even under Prop 13, which matters for commercial buyers.

Found the statute but unsure how to apply it? Your county assessor's office is legally required to explain how they calculated your assessment. Ask for the property record card and the market value estimate behind your assessed value. That record is almost always public.

Frequently asked questions

What does a 100% assessment ratio actually mean?

It means the assessor is supposed to value your property at full market value, the price a willing buyer would pay a willing seller with no pressure on either side. In practice, equalization studies often show the actual ratio drifts below 100% in many 100% states. For appeals, the key question is whether your specific property is assessed above or below the county's actual common level ratio.

My assessed value is lower than my purchase price. Can I still appeal?

Yes, though your odds drop. If your assessed value implies a market value below what you paid, the assessor may argue your sale price is the best evidence of value. Even so, if the market has declined since your purchase, or you paid above market, you may still have an argument. Pull comparable sales from the last six months. If they support a value below your implied assessed market value, appeal.

How does Colorado's assessment ratio work? It seems to change every year.

Colorado's residential assessment rate has changed repeatedly through legislation. House Bill 23-1311 set it at 6.765% for tax years 2023 and 2024 as part of property tax relief. Before that it was 6.95% for 2022. The legislature sets the rate and can change it. The Colorado Division of Property Taxation publishes the current rate each year. Multiply your residential market value by the current rate to get your assessed value.

Does the assessment ratio apply to my land value and building value separately?

In most states, the ratio applies to the total assessed value of the parcel, land plus improvements combined. A few states assess land and improvements separately but apply the same ratio to both. Your property record card from the assessor shows the breakdown. For appeal purposes, the combined total is usually what matters, unless you are disputing the land-versus-improvement split, which is more common in commercial appeals.

What is a sales ratio study and where do I find my county's results?

A sales ratio study compares assessed values to actual sale prices for properties that sold in a given year. The ratio (assessed divided by sale price) tells you how close the assessor's values are to market. States run these to equalize funding and audit local assessors. Find your county's results on your state department of revenue or tax commission website, usually under property tax equalization, assessment reports, or similar headings.

Can the assessment ratio be different for my home versus a rental property next door?

Yes, in classified property tax states. Illinois, New York, Minnesota, South Carolina, and many others apply different ratios or class rates to different property types. Owner-occupied homes often get a lower ratio than rental residential or commercial property. The classification on your property record card determines which ratio applies to you. If your property is misclassified, correcting that can cut your assessment independent of any market value argument.

Missouri's assessment ratio is 19% for residential. How do I calculate what I owe?

Take the appraised market value your assessor set and multiply by 19%. That gives your assessed value. Then multiply by your local levy rate (expressed as a dollar amount per $100 of assessed value or as a mill rate). Your county collector's office publishes levy rates for every taxing district that applies to you. Missouri's 19% ratio is set in the state constitution, Article X §4(b), and cannot change without a constitutional amendment.

Is there a federal law that controls what assessment ratio states can use?

No. Assessment ratios are entirely a state and local matter under the Tenth Amendment. The only federal constitutional limit comes from uniformity and equal protection principles. The U.S. Supreme Court held in Allegheny Pittsburgh Coal Co. v. County Commission (1989) that wildly disparate assessments within a single jurisdiction can violate the Equal Protection Clause, but that case has narrow reach. States set their own ratios through constitutions, statutes, and administrative rules.

How do I know if my county's actual assessment ratio matches the statutory ratio?

Request or download your state's most recent equalization or sales ratio study. It shows the median assessment-to-sales ratio for your county, ideally broken out by property class and sometimes by value tier. Compare that median to the statutory ratio. A gap of more than a few percentage points means the county is missing its statutory target, which creates both an equalization issue and individual appeal openings for properties assessed above the actual common level.

Does Texas really use a 100% assessment ratio? It feels high.

Yes. Texas law requires appraisal districts to appraise all property at 100% of market value as of January 1 each year. Texas Tax Code §23.01 states: "All taxable property is appraised at its market value as of January 1." ^[13] The Texas Comptroller audits this with a biennial Property Value Study by school district. Some districts come in below 100% in practice, but the standard and the accountability are real. Homestead exemptions and the 10% annual homestead value cap provide relief independent of the ratio.

If my state has a low ratio like 10%, is it even worth appealing a small dollar difference in assessed value?

Run the math first. A $5,000 error in assessed value in a 10% ratio state means the assessor thinks your home is worth $50,000 more than it should be. At a 2% effective tax rate, that costs you $1,000 a year. Most residential appeals cost nothing to file and take a few hours to prepare. That is almost always worth it. The percentage error, not the dollar size of the assessed value, tells you how much you are overpaying.

What is the difference between the assessment ratio and the mill rate?

They work together to produce your tax bill. The assessment ratio turns your market value into taxable assessed value. The mill rate (also called levy rate or tax rate) turns that assessed value into dollars owed. One mill equals $1 of tax per $1,000 of assessed value. A 20 mill rate on a $100,000 assessed value produces a $2,000 bill. The ratio sets the assessed value; the mill rate sets what fraction of it you pay each year.

How often does the assessment ratio change?

Statutory ratios set in constitutions rarely change and require ballot measures or amendments. Legislative ratios change when the legislature acts. Colorado has moved its residential rate several times in recent years through legislation. Iowa's rollback fraction changes annually by formula in state code. Equalization ratios that reflect actual practice change every year based on sales data. Check your state's current-year published ratio rather than trusting a figure from even two or three years ago.

Sources

1. Alabama Secretary of State, Alabama Constitution Article XI §217: Alabama's assessment ratio for residential property is 10% of fair market value, set in the state constitution
2. Arizona State Legislature, A.R.S. §42-15002: Arizona's assessment ratio for residential property (Class 3) is 10% of full cash value
3. California State Board of Equalization, Proposition 13 overview: California uses a 100% market value standard with annual increases capped at 2% or CPI under Proposition 13, Article XIIIA of the California Constitution
4. Georgia General Assembly, O.C.G.A. §48-5-7: Georgia law requires all real property to be assessed at 40% of fair market value
5. Illinois General Assembly, 35 ILCS 200/9-145 and 9-150: Illinois uses a 33.33% assessment ratio statewide; Cook County residential property is assessed at 10% of market value under 35 ILCS 200/9-150
6. Lincoln Institute of Land Policy, 50-State Property Tax Comparison Study, 2023: Assessment-to-market ratios, mill rates, and effective tax rates by state and property class; Cook County commercial property tax burden among highest in the nation
7. New Jersey Division of Taxation, Common Level Ratio tables: New Jersey publishes annual Common Level Ratios by municipality; these ratios, not the statutory 100%, are the operative standard for tax appeals under N.J.S.A. 54:4-23
8. Minnesota Department of Revenue, Property Tax Classification Rates: Minnesota assesses property at 100% of market value but applies class rates before the mill rate; agricultural homestead has a 0.5% class rate on the first $500,000 versus 1.5% for commercial-industrial property
9. U.S. Supreme Court, Allegheny Pittsburgh Coal Co. v. County Commission, 488 U.S. 336 (1989): The Supreme Court held that grossly disparate property assessments within a single jurisdiction violate the Equal Protection Clause of the Fourteenth Amendment
10. University of Chicago Harris School of Public Policy, assessment regressivity research (with ProPublica), 2021: Lower-value homes in many jurisdictions are assessed at effective ratios systematically higher than higher-value homes in the same county, documenting regressive assessment patterns in Cook County and other large jurisdictions
11. International Association of Assessing Officers (IAAO), Standard on Ratio Studies: IAAO standards define acceptable assessment uniformity and recognize that achieving uniform ratios across property value strata is a persistent technical challenge in mass appraisal
12. Texas Comptroller of Public Accounts, Property Value Study: The Texas Comptroller conducts a biennial Property Value Study measuring assessment accuracy by school district; Texas Tax Code §23.01 requires appraisal at 100% of market value