Property tax math feels intimidating because every state does it differently. This guide unpacks the three most common confusion points: assessment ratios, millage rates, and equalization factors.
Almost every U.S. property tax bill follows a version of this formula:
Tax bill = (Assessed Value − Exemptions) × Tax Rate
The complexity comes from how each state defines "assessed value" relative to market value, and how different layers of taxing authorities (state, county, city, school district, special districts) combine into the final tax rate.
The assessment ratio answers: what fraction of market value gets taxed?
| State | Assessment ratio | Note |
|---|---|---|
| Texas | 100% | Full market value (Texas Tax Code §23.01). 10% Homestead Cap limits year-over-year increases. |
| California | Acquisition value | Set at change of ownership; ≤2% annual factored increase (Prop 13). Not a fixed ratio — depends on when you bought. |
| Illinois | 33⅓% | Statutory ratio for non-Cook counties (35 ILCS 200/9-145). Cook uses 10% via classification ordinance. |
| New Jersey | True market value | Each municipality assesses at full market value, with annual Director's Ratio adjustment for state comparison. |
| New York | Variable level of assessment | Each locality sets its own — some at 100%, others at fractional (e.g., 65%). Equalization rate published annually by ORPTS. |
| Florida | 100% just value; Save Our Homes 3%/CPI cap applied to assessed value of homestead | Full market just value as of Jan 1 (FL Stat. §193.011); SOH §193.155 caps homestead assessed value (not just value) at lower of 3% or CPI annually. |
| Massachusetts | 100% full and fair cash value | Full market value standard (Mass. Gen. Laws Ch. 59 §38). Annual revaluation + DOR triennial certification. |
| Connecticut | 70% | Uniform 70% statewide ratio (Conn. Gen. Stat. §12-62a) applied to all real property. Mill rates vary 6× across municipalities (Hartford 68.95 vs Greenwich ~11). |
| Pennsylvania | County-set predetermined ratio (PDR) | Most counties at 100%, but the Common Level Ratio (CLR) published annually by STEB can substitute on appeal when 15%+ below PDR. |
| Ohio | 35% | Statutory ratio (ORC 5713.03) applied uniformly. Owner-occupied residential gets automatic 10% Reduction Factor + 2.5% Rollback applied to taxes charged (ORC 319.301-302) — these reduce the bill, not the assessed value. |
| Georgia | 40% | Uniform 40% ratio (O.C.G.A. §48-5-7) applied to all property. Conservation land under CUVA (§48-5-7.4) gets use-value vs. fair-market assessment. |
| North Carolina | 100% | No fractional assessment ratio (G.S. 105-283) — appraised value is assessed value. Statewide median effective rate ~0.69%; the lack of a fractional ratio means NC's nominal millage looks lower than other states even when effective burden is comparable. Schedule of Values (G.S. 105-317.1) governs every county's mass appraisal — challenging the SOV's application to your parcel is the higher-leverage appeal path versus pure market-value challenges. |
Why ratios matter for appeals: if your state uses a fractional ratio (IL 33⅓%, CT 70%, OH 35%, GA 40%, NY variable), your assessment in dollars is not directly comparable to market value. You appeal the implied market value: assessed value ÷ ratio. So for a CT property with assessed value $350,000, the implied fair market value is $500,000 — that's the number to compare against recent comp sales.
Pennsylvania's CLR substitution is unique. When the state-published Common Level Ratio falls more than 15% below the county's predetermined ratio, an appellant can substitute CLR in the math under 53 Pa.C.S.A. §8854. Allegheny County's 2026 CLR is 50.1% — meaning successful appellants compute assessed value at 50.1% of FMV instead of the 100% PDR, often producing ~50% reductions even on uncontested fair-market values.
Florida's two-rolls structure is also unique. Florida maintains both a just value roll (full market) and an assessed value roll (capped by Save Our Homes for homesteads). Long-tenured homesteads can have just values 2-3× their capped assessed values — so a successful market-value appeal won't always reduce the tax bill if SOH is the binding constraint.
Tax rates are expressed differently by state:
Per $100 of assessed value — Texas, NJ, IL
As a percentage — California, some others
Convert between formats:
A typical residential rate in our coverage states:
California: $1.10 per $100 (1.1% effective, capped by Prop 13's 1% rate + ~0.1% local debt service)
Illinois: ~$2.07 per $100 (2.07% effective, varies by county)
New Jersey: ~$2.20 per $100 (2.20% effective, highest in U.S.)
New York: ~$1.60 per $100 (1.6% effective, varies enormously by locality)
Equalization is the mechanism states use to reconcile inconsistent local assessment practices:
New Jersey: Director's Ratio published annually by the NJ Director of Taxation; used in Chapter 123 (N.J.S.A. 54:3-22) appeals — if your assessment-to-true-value ratio falls outside ±15% of the Director's Ratio, the County Board of Taxation must adjust to bring it into the common level range
New York: ORPTS publishes annual equalization rates for cross-jurisdictional comparison and certain state-aid calculations
Texas: state equalization is implicit (each CAD reappraises to 100% market annually)
California: no equalization in the IL/NJ sense; Prop 13 acquisition-value system makes it unnecessary
If you don't understand assessment math for your state, you can:
Pull your local equalization rate or Director's Ratio. This is the procedural lever in IL/NJ/NY for unequal-assessment claims.
Compare assessment-to-true-value ratios, not absolute assessed values. Cross-property comparisons only make sense at the same ratio.
California Property Tax Appeals — The Complete Guide (Prop 13 + Prop 8)
Illinois Property Tax Appeals — The Complete Guide (33⅓% + Cook 10% + state multiplier)
New Jersey Property Tax Appeals — The Complete Guide (Chapter 123 Common Level Range)
New York Property Tax Appeals — The Complete Guide (variable level of assessment + equalization rate)
California Revenue & Taxation Code §50, §51 — leginfo.legislature.ca.gov
35 ILCS 200/ Property Tax Code — ilga.gov
N.J.S.A. 54:3-22 (Common Level Range)
NY Real Property Tax Law (RPTL) — nysenate.gov
The Property Tax Desk Editorial Team