County Tax Roll
A county tax roll is the official public record a county maintains for property taxation: every parcel, its owner of record, the owner's mailing address, assessed value, exemptions, and sale history. It is the primary source that virtually all commercial property data resells.
Why the tax roll is the root source
Counties must know who owes tax on every parcel, so the roll is kept current by law — typically refreshed within weeks of a recorded sale. Everything a lead vendor sells about ownership traces back to it: owner names, tenure (from the last sale date), absentee status (mailing vs. property address), and exemptions like homestead. Commercial providers add value by normalizing thousands of counties into one schema, but the underlying facts are public.
What varies by county
Access and completeness differ widely. Most counties publish the roll through public GIS services; some redact owner names online (common in California) even though ownership remains public record at the assessor's office; formats and refresh cadences vary. That variance is why "which counties are covered, and with which fields" is the right question to ask any property-data tool — WhoseTitle publishes exactly that on its coverage map.