How we source, estimate, review, and correct
Last updated
Home buyers use this site to plan one of the largest purchases of their lives, so we hold it to a simple standard: every county-specific number traces to a public source, every estimate is labeled as one, and every error we find or are told about gets fixed and logged. This page explains how that works.
Independence
- We work only for buyers.No agent referrals, mortgage leads, or affiliate links. Outbound links go to primary public sources, which don't pay us.
- No ads or sponsored content. Nobody can pay to change what a page says or how a county is ranked.
- One revenue source. The site is funded by a companion mobile app that buyers pay for directly.
How we source data
County-specific figures come only from public datasets, and each county page links to the exact table or official page behind its numbers:
- Property tax and home values: US Census Bureau American Community Survey 5-year estimates, tables B25103 (median real estate taxes paid) and B25077 (median home value).
- Transfer taxes and exemptions:each state's Department of Revenue, tax commission, or statute, checked by hand against the official page.
- Flood exposure:FEMA's National Risk Index.
Field-by-field definitions, data vintages, and validation rules are in our methodology.
How estimates are built
Some costs aren't published county by county. For those, the calculator uses national ranges and fixed assumptions, and says so on the page:
- Closing cost line items (title insurance, appraisal, inspection, origination, attorney fees) are national ranges from the CFPB, ALTA, and industry surveys, shown as low–high ranges rather than single numbers.
- Mortgage payment, insurance, and PMI use stated assumptions. The interest rate is the current Freddie Mac national average for the term you pick, shown with its survey date; insurance and PMI are fixed assumptions. Your lender and insurer replace all of them with real quotes.
- County data stays separate.Estimates never overwrite or blend into the county's published tax rate, home value, or transfer tax.
- No renovation cost estimates.Local labor costs can't be sourced reliably, so we flag conditions to inspect instead of guessing at repair prices.
Every assumption is listed in calculator assumptions.
How content is written and reviewed
- Numbers come from the data, not from writers. Rates, rankings, tables, and dollar figures are generated directly from our source datasets.
- County summaries are generated from the data. The short paragraph on each county page is built by a script from that county's figures, so it can't drift from the numbers beside it.
- Guides are AI-assisted and human-reviewed. Article drafts are written with AI assistance, then checked and edited by the countyhomecosts Editorial Team before publication. Each guide lists the sources it relies on.
- Not professional advice.We explain costs and risks; we don't give legal, tax, or financial advice. Verify figures with a licensed professional before you sign.
How often data is updated
| Data | Refreshed |
|---|---|
| Census ACS property tax and home values | Each year, when the Census Bureau releases a new 5-year vintage |
| State transfer taxes and exemptions | At least yearly, and when a state changes its law |
| FEMA National Risk Index | When FEMA publishes a new version |
| Mortgage rates (Freddie Mac PMMS) | Weekly, the day after Freddie Mac publishes |
| Closing cost ranges and other calculator assumptions | At least yearly |
Each county page shows when it was last updated and which data vintage it uses.
Corrections
If you spot a wrong rate, a stale transfer tax, or a missing exemption, use the contact form and include the page URL, what looks wrong, and the source you're reading.
- We check the report against the primary source within 48 hours.
- If it holds up, we fix the underlying data file so every affected page updates together, and the pages' "Updated" date changes with it.
- We list the correction below with the date and what changed.
Corrections log
No corrections have been made since this policy was published on September 21, 2026.