Reading an effective property tax rate
Property tax is the largest running cost of a house after the mortgage, and the only one that comparison sites routinely get wrong — because the number they quote is a component, not a bill.
Ask what the property tax rate is in a town and you will usually be given the city's rate. It is a real number and it is a minority of what you pay. The bill that arrives is the sum of several taxing bodies that happen to overlap on your parcel: the city, the county, the school district, and depending where you are, a community college district, a hospital district, a library or fire district, and a special assessment tied to your subdivision.
None of them coordinate. A house can sit in a town with a modest city rate and an expensive school district, or the reverse, and the listing will quote whichever number is flattering.
What the rate on this site is
Rather than adding up rates — which is impossible to do uniformly for every town in the country, because the list of taxing bodies differs everywhere — this site computes the effective rate: the total real estate taxes actually paid by owners in a town, divided by the total value of what they own.
It comes out of the Census, from owners reporting both figures, so it captures every overlapping district at once without needing to know which ones exist. If a town has five taxing bodies, all five are in the number, because the owners paid all five.
Two properties of that approach are worth understanding.
It is an average across all owner-occupied homes, not a rate applied to a purchase price. Where a state limits how fast assessments can rise for existing owners, long-term owners are taxed on values far below what their homes would sell for — and the effective rate across the town comes out well below what a new buyer would face. California's assessment limits are the sharpest example, and anywhere with a homestead cap has a milder version of it.
It uses aggregates rather than medians, because the Census tops out its published median tax at a fixed ceiling, and in expensive towns that ceiling makes a median meaningless. Total taxes divided by total value stays honest at any price level.
The effective rate tells you what a town's owners pay on average. It does not tell you what you would pay on the house you are looking at.
What it leaves out
Special district assessments are not property tax and do not appear in it. They go by different names in different states — MUD and PID in Texas, CDD in Florida, Mello-Roos in California, SID elsewhere — and the pattern is the same: a newer subdivision borrows to build its own roads, water and drainage, and the owners repay it through a charge that runs for decades.
These are attached to specific parcels, not to towns, so no town-level figure can include them. On a new-build they can add meaningfully to a monthly payment, and they are the single most common unpleasant surprise at closing. The only way to know is to ask the county appraisal district about the specific parcel.
Exemptions are also outside the number. Homestead, senior, veteran and disability exemptions can each move a bill substantially, and they apply to people rather than to houses.
Using it properly
The effective rate is built for one job: comparing the tax burden of one town against another on the same basis. It does that well, and a spread of half a percentage point between neighbouring suburbs — which is common — is thousands of dollars a year on a typical house.
Use it to sort. Then, for the house you actually want, get the bill from the county: the assessed value, the districts that levy on it, the exemptions you would qualify for, and whether there is a special assessment. That is a ten-minute phone call and it is the only number that is yours.