Assessor Property Records Contain Wrong Square Footage for Millions of Homes

County assessor databases frequently list incorrect square footage, bedroom counts, or structural features for residential properties. When counties digitized paper records, data entry errors were rampant -- entire floors were omitted, garages were counted as living space, or demolished additions remained on file. Because assessors only update records after a sale or permitted remodel, a home that hasn't sold in 20 years may still carry decades-old errors. This matters because property tax is calculated directly from assessed value, and assessed value is driven heavily by recorded square footage. A homeowner overcharged by 200 sq ft at $150/sq ft in a jurisdiction with a 1.2% tax rate pays an extra $360/year indefinitely. The structural reason this persists is that assessors have no systematic process for auditing existing records against reality -- they rely on homeowners to discover and report the errors themselves, but most homeowners never look at their property record card.