Open data
Verified property tax appeal deadlines
A machine-readable list of appeal filing windows. A row is included only when a person has verified its dates and rules against the official source; predicted windows carry an expected range instead of a date. Always confirm the deadline printed on your own notice.
What files are available?
- Formats
- JSON, CSV
- Last changed
- October 2, 2026
- Verified windows
- 506
- 123 county guides
506 verified window(s) across 123 county guide(s).
Which fields does each row have?
| Column | Meaning |
|---|---|
jurisdiction_id | County id (stable slug) |
state | State name |
county | County name |
level_id | Appeal body id |
body_name | Appeal body |
subject_id | Township or county the window applies to |
subject_name | Its name |
tax_year | Tax year |
status | predicted, announced, confirmed, extended, closed or cancelled |
opens_on | First filing day (ISO date), if published |
closes_on | Last filing day (ISO date); empty for predicted windows |
closes_at_local | Local cutoff time, if published |
expected_close_earliest | Predicted windows only: earliest expected close |
expected_close_latest | Predicted windows only: latest expected close |
filing_semantics | When a filing counts as on time (verified rule) |
source_urls | Official sources behind the row (space-separated) |
claim_ids | Knowledge-base claim ids behind the row |
last_verified | Latest verification date of those claims |
page_url_path | Guide page for this window |
How is the data verified?
Each window cites knowledge-base claims: the official calendar row for that township and the body’s deadline rule. Each claim stores a verbatim quote and the source address, and a person other than its researcher checks the quote against the source. Read the verification process.