Two homes at the same purchase price can carry monthly payments that differ by $500 or more, almost entirely because of property taxes. Effective rates vary by an order of magnitude across the country and can shift again at reassessment. Modeling them up front is the only way to know the real cost of ownership.
The Range Is Larger Than Most Buyers Expect
The national average effective property tax rate is roughly 1 percent of home value per year. The range around that average is wide:
- Lower-tax states (Hawaii, Alabama, Colorado, Nevada, Louisiana) generally fall in the 0.3 to 0.6 percent range.
- Higher-tax states (New Jersey, Illinois, New Hampshire, Connecticut, Vermont, Texas) generally fall in the 1.7 to 2.5 percent range.
On a $500,000 home, the gap between a 0.5 percent state and a 2.5 percent state is $10,000 per year, roughly $830 per month, or about $300,000 over a 30-year ownership horizon.
Within a single state, town-by-town rates can vary by a factor of two or three. In Connecticut, mill rates range from roughly 11 in Greenwich to over 75 in Hartford. The selected town can outweigh the selected state in the final tax bill.
How Property Tax Is Calculated
Two inputs determine the bill:
- Assessed value. What the local assessor records as the value for tax purposes. Many jurisdictions apply an assessment ratio rather than using full market value (Connecticut, for example, uses 70 percent).
- Mill rate (or tax rate). The dollars of tax per $1,000 of assessed value. A mill rate of 30 means $30 of tax per $1,000 of assessed value.
A Connecticut home with $400,000 market value, assessed at 70 percent ($280,000), in a town with a 35 mill rate, owes $280,000 × 0.035 = $9,800 per year, or roughly $817 per month in property tax alone. Other states use a flat percentage of market value, sometimes adjusted by homestead exemptions, senior freezes, or veterans' exemptions.
The Reassessment Trap
Assessed value is often stale at purchase. Most jurisdictions reassess on a 3 to 5 year cycle, some less often. A home purchased after a stretch of price appreciation but before the next reassessment can see its tax bill rise meaningfully when the catch-up assessment occurs, sometimes 20 to 50 percent.
Some states cap the year-over-year increase in assessed value: California's Prop 13 caps it at 2 percent, Michigan at 5 percent, Oregon at 3 percent. In states without such caps, the reassessment after a hot market can produce a payment increase that was not reflected in the listing's estimated tax figure.
Two practical checks before purchase: when the property was last assessed, and how current assessed value compares to recent sale prices in the area. If assessed value is far below comparable sales, a corrective reassessment is likely.
Escrow and Why the Payment Changes
On most mortgages, the servicer collects 1/12 of the estimated annual tax bill each month into an escrow account and pays the bill when due. This is why a fixed-rate mortgage can have a changing monthly payment: when the tax bill rises, the escrow contribution rises with it.
Servicers run an annual escrow analysis. If taxes rose during the past year and the escrow ran short, the new monthly payment includes both the higher ongoing escrow contribution and a recovery for the prior shortfall. A $100 to $300 monthly payment increase in a reassessment year is not unusual.
What the Tax Funds
Property taxes typically fund schools, roads, police, fire, libraries, and parks. In most jurisdictions, 60 to 70 percent goes to public schools, which is why school quality and property tax rates correlate closely and why a high-tax town is often also a high-amenity town.
Treating property tax as pure cost overlooks the service bundle it funds. A higher annual tax bill in a town with strong public schools can substitute for tens of thousands of dollars in private school tuition; a lower tax bill in a town with weaker schools can shift that cost to the household budget without the partial deductibility.
A Tax-Adjusted Approach to Shopping
- Compare homes by total monthly cost, not by purchase price. A $450,000 home at 2.3 percent tax costs roughly the same monthly as a $525,000 home at 1.0 percent tax (on the same mortgage terms).
- Model the next reassessment. Confirm the current assessed value, the date of the last assessment, and recent comparable sale prices. Assume the next reassessment will move toward those comparable sales.
The SALT Deduction
Since 2018, the federal SALT (state and local tax) deduction has been capped at $10,000 combined across state income tax, property tax, and local taxes. In high-tax states, this means most property tax above the cap is not federally deductible. The cap is scheduled to expire at the end of 2025 unless extended; after-tax modeling should reflect whichever rule applies in the relevant year.
Special Assessments and Hidden Line Items
- Special assessment districts. Additional levies for specific improvements (sewer expansions, sidewalk installation, school bond issues), often temporary but sometimes running 10 to 20 years.
- Mello-Roos (California). Infrastructure bonds attached to newer-development property taxes; can add substantially to the effective rate.
- Fire, water, and mosquito-control district fees. Itemized separately in some jurisdictions outside the base mill rate.
The authoritative source is the property tax card at the assessor's office or online portal, not the listing's estimated tax line. The listing figure is usually based on current assessed value and does not reflect a sale-triggered or scheduled reassessment.