Data Methodology & Editorial Standards

Data Source

All property tax data on TaxByCounty comes from the U.S. Census Bureau American Community Survey (ACS) 5-Year Estimates, covering the period 2019-2023. We use two specific data tables:

• Table B25103 — Median real estate taxes paid (overall, with mortgage, without mortgage)
• Table B25077 — Median home value

The Census Bureau collects this data through surveys of approximately 3.5 million households annually. The 5-year estimates provide the most reliable data for all geographic areas, including small counties.

How We Calculate Effective Tax Rate

The effective property tax rate is our primary comparison metric. It is calculated as:

This rate is more useful for comparison than the nominal mill levy because it accounts for differences in how states and counties assess property values. A county with a high assessment ratio and low mill levy may have the same effective rate as one with a low assessment ratio and high mill levy.

Update Frequency

We update our data when the Census Bureau releases new ACS 5-Year Estimates, typically in December of each year. Our current dataset reflects the 2019-2023 survey period. When new data becomes available, we re-process all 3,100+ counties simultaneously to ensure consistency.

Data Quality

The Census Bureau suppresses data for counties where the sample size is too small to produce reliable estimates. We display these as "N/A" rather than showing potentially misleading numbers. Our pipeline automatically:

• Converts Census sentinel values (e.g., -666666666) to null
• Validates that effective rates fall within reasonable bounds
• Cross-checks county FIPS codes against the Census geographic hierarchy
• Flags outliers for manual review

Editorial Independence

TaxByCounty is part of the ByCounty Network. Our site includes affiliate links to property tax appeal services (such as Ownwell) and mortgage comparison tools. These partnerships never influence the data we present. All tax rates, median values, and rankings are derived directly from Census Bureau data with no adjustments. Affiliate relationships are clearly disclosed on every page where they appear.

AI-Generated Content

TaxByCounty uses artificial intelligence (Claude by Anthropic) to generate narrative descriptions on county and state pages. These narratives translate raw Census data into readable summaries that help users understand their county's property tax landscape.

Our AI content pipeline works as follows:

• Input: Raw Census ACS data (median tax, median home value, effective rate) for each county
• Processing: Claude generates contextual narratives comparing the county to state and national averages
• Verification: All generated narratives are reviewed for factual accuracy — every statistic cited must match the Census source data
• Presentation: Narratives appear in the "Data Story" section on county pages and "State Overview" section on state pages

AI-generated content is supplemental to the primary data tables, calculators, and statistical comparisons. The underlying numbers are always derived directly from Census Bureau data with no AI modification. If you spot any inaccuracy in a narrative, please let us know.

Questions or Corrections

If you believe any data on TaxByCounty is incorrect or if you have questions about our methodology, please contact us. We take data accuracy seriously and will investigate all reports promptly.