Guidesfrom the federal index
Why Your Property Tax Bill Differs From the Effective Rate
The county rate is one median bill over one median value. Assessment ratios, exemptions, caps and district millage put your own bill somewhere else; here is how.
The short answer
The effective rate on a county or city page is one bill divided by one home value, both medians of everyone who owns their home there. Your bill is set by your assessor and the districts you live in: a stated assessment ratio, exemptions that come off before the rate applies, caps that hold an older assessment below the market, and a millage that differs between the school district on one side of a road and the one on the other. The median is the right number for “what do homeowners here pay”; it was never going to be your number. The property tax rate pages print both inputs and the margin of error so you can see how much of the gap is the arithmetic and how much is you.
What the rate is
Effective rate = median real estate taxes paid ÷ median owner-occupied home value
Both figures come from the Census Bureau’s American Community Survey, ACS 2020-2024 5-year estimates: table B25103 asks owners what they paid in real estate taxes in the last year, and table B25077 asks what they think the home would sell for. The survey reports the median of each, with a margin of error at the 90% level, and five years of answers are pooled so that small places have a usable sample. Dividing the two medians gives the share of a typical home’s value that goes to property tax in a typical year, after whatever exemptions those owners already had.
A worked example: one value, four rates
Travis County, Texas: $7,727 median taxes paid ÷ $523,000 median value = 1.48%, with a margin of ± 0.03%. Now take that one county median value, $523,000, and apply the rate of each area it sits in:
| Area | Median taxes | Median value | Rate | $523,000 × rate |
|---|---|---|---|---|
| Austin (city) | $8,024 | $555,300 | 1.44% | $7,557 |
| Travis County | $7,727 | $523,000 | 1.48% | $7,727 |
| Texas | $4,232 | $283,800 | 1.49% | $7,799 |
| United States | $3,119 | $332,700 | 0.94% | $4,903 |
The same $523,000 home “pays” $7,727 at the county rate and $4,903 at the national rate, a gap of $2,824 a year with nothing changed but which median you divided by; the city and the state sit within a few dollars of the county here, which is its own lesson about how much of the rate is set statewide in Texas. That is the first thing to know about an effective rate: it is a property of the area you chose, and the smallest area with a usable sample is the one to read. The second is the margin: Travis County’s 1.48% is really a range of about 1.45% to 1.51%, and smaller counties carry much wider ones.
Four reasons your own bill sits somewhere else
The assessment ratio
Many states tax a stated fraction of market value, not the whole of it. The nominal rate on your notice is applied to that assessed value, so a published millage can look nothing like the effective rate and still produce it. The median already has this baked in; your notice shows the ratio your assessor uses, and the assessment guide is the place to check the assessed value itself.
Exemptions
Homestead, senior, disability and veteran exemptions take an amount or a share off the taxable value before the rate applies. The owners in the survey reported what they actually paid, so the median rate is net of the exemptions those owners had. If yours are larger than typical, your rate is lower; a new owner who has not filed yet is above it.
Caps and reassessment schedules
Several states limit how much an assessment can rise in a year while the same owner stays, and others reassess only every few years. A long-time owner’s taxable value can sit far below what the home would sell for, and the survey’s value question asks about the sale price, not the taxable one. The median mixes long-time and recent owners; a buyer who closed last year is taxed on a reset value and pays more than the median suggests.
Which districts you are in
A county rate is a blend of every school district, city, hospital district and special district inside it. Two homes a mile apart in different school districts pay different millages. Where a city page exists it is the closer fit, and it is still a blend.
Why the value side matters
The survey’s home value is what owners said in 2020 to 2024. The Travis County home price page carries the FHFA House Price Index, which measures how prices in the county moved since then and since you bought. If values rose after the survey window and assessments followed, the bill on a current value is higher than the median suggests; if they fell, lower. The index has the usual limits: it tracks the area, not your house; renovations, condition and lot are invisible to it; it is built from repeat sales on conforming mortgages, so cash, jumbo, FHA and VA sales are not in it; and it is not an appraisal.
What this guide does not cover
- Any state’s actual ratio, exemption amounts, cap or millage. They are read off your notice, never modeled here.
- Whether a bill is wrong. The rate is a benchmark for the area; appeals turn on the property record and comparable sales.
- Renters, second homes and commercial property, which the two tables exclude.
Sources
This guide is for informational purposes only. It is not an appraisal, and not financial, tax, lending or real-estate advice. Every estimate on this site tracks an area’s average, never a particular house. Confirm anything that matters with a licensed appraiser or your lender.
Last reviewed: October 2026 · Against Census ACS 2020-2024 5-year estimates, tables B25103 and B25077 (pulled 2026-10-08).