How we source and compute every number on this site

Property tax rates and median home values

Source

US Census Bureau, American Community Survey (ACS) 5-year estimates. Accessed via the Census API at api.census.gov.

Vintage

2024 (covering survey years 2020–2024). Released December 2025 by the Census Bureau.

Tables used

B25103_001E (median real estate taxes paid) and B25077_001E (median home value), joined on the county GEOID (5-digit FIPS).

Effective tax rate

Computed as median real estate taxes paid divided by median home value. This is the actual effective rate homeowners pay — not the nominal millage rate, which differs due to assessment ratios and exemptions.

Validation

All counties must have a 5-digit FIPS, effective rate under 5%, and median home value over $50,000. Territories (Puerto Rico, USVI, Guam, American Samoa, Northern Mariana) are excluded. 3,134 counties across the 50 states plus DC passed validation.

Update cadence

Annually each December when the Census Bureau releases the next 5-year ACS vintage.

State real estate transfer taxes

Source

Primary source per state: the state Department of Revenue, Tax Commission, or authorizing statute. Every entry in data/transfer_taxes.json links to a live .gov URL.

Verified

April 2026. All 51 jurisdictions (50 states plus DC) were individually researched against their authoritative source.

What we capture

Buyer rate, seller rate, whether counties can add their own transfer taxes, any notable county-level additions (e.g., NYC RPTT, Chicago CTA portion, Miami-Dade surtax), and the source URL for each. Rates are decimal fractions, not percentages.

Custom vs. statute

Where statute says "either party" and custom assigns payment to the seller or buyer, we record custombecause that's what you'll actually owe at closing.

Update cadence

Annually, or when major legislation changes the rate (e.g., Rhode Island's 63% increase effective January 2026 was captured in the current data).

Flood zone risk and SFHA percentage

Source

Federal Emergency Management Agency (FEMA), National Risk Index (NRI), county-level feature layer. Queried via the published ArcGIS FeatureServer.

Vintage

NRI version 1.20 (December 2025).

SFHA percentage

Computed as (Coastal Flood Exposure Area + Inland Flood Exposure Area) ÷ Total County Area, using FEMA's CFLD_EXP_AREA, IFLD_EXP_AREA, and AREA fields. Result is the share of county land within a Special Flood Hazard Area.

Risk buckets

LOW (<5%), MODERATE (5–15%), HIGH (15–30%), VERY_HIGH (>30%).

Coverage

3,144 US counties. This is the authoritative FEMA aggregate — not a parcel-level flood zone lookup. For specific properties, users are directed to msc.fema.gov.

Update cadence

Annually when FEMA releases a new NRI version.

Closing cost components

Sources

Consumer Financial Protection Bureau (CFPB), American Land Title Association (ALTA), Bankrate 2025–2026 closing cost survey, Angi/HomeAdvisor cost databases for inspection and appraisal ranges, Fannie Mae and Rocket Mortgage for loan origination norms.

Components covered

Title insurance, loan origination, appraisal, home inspection, attorney fees (attorney-required states only), recording fees, prepaid interest, insurance escrow, and property tax escrow.

Caveat

These are national ranges, not county-specific. Title insurance rates are regulated in FL, TX, and NM; attorney fees only apply in attorney-required closing states. The calculator applies the correct subset based on the county's state.

Update cadence

Re-verified annually against the latest CFPB and Bankrate surveys.

State property tax exemptions

Source

Primary source per state: Department of Revenue, Tax Commission, or statute. All 51 jurisdictions individually researched. Every exemption in data/state_exemptions.json links to a live .gov URL.

Categories captured

Homestead, senior (65+), disabled veteran, general disability, assessment caps (e.g., California Prop 13, Michigan Proposal A, Texas 10% cap), first-time buyer programs, and agricultural/current-use.

What we do NOT capture

County-level local exemptions that supplement state programs. For example, Texas school districts each set their own local homestead amount above the state minimum. Users are directed to their county assessor for final verification.

Verified

April 2026.

What we deliberately don't do

• No affiliate links. No mortgage lender, title company, or agent referrals. The site earns revenue only from the companion mobile app — not from steering buyers.
• No ads. No display ads, no sponsored content. Pages load fast because they carry no ad JavaScript.
• No invented data.Every figure traces to a public source. Where we don't have data for a county, the page says so — we don't fill gaps with estimates.
• No per-property flood zone lookup. Our flood data is a county-level FEMA aggregate. For your specific property, use msc.fema.gov.

Reproducibility

The data pipeline is open and scriptable. Every dataset on the site can be regenerated from its public source:

• scripts/build-counties-csv.mjs — pulls the Census ACS data and produces counties.csv
• scripts/build-flood-zones.py — queries FEMA NRI and produces flood_zones.csv
• scripts/build-county-narratives.mjs — generates per-county narrative paragraphs deterministically from the data files
• scripts/build-llms-full.mjs — generates the llms-full.txt index for LLM crawlers

Transfer taxes and state exemptions are maintained as hand-verified JSON files because they require live .gov source verification; running a script against the state DOR pages would not be reliable.