A county assessor's maps are just accurate enough to stand up in court for the purpose of determining who owes the taxes on a parcel and where that parcel is generally located. The county assessor is under no obligation to even provide online web maps, let alone provide survey-grade mapping.

How accurate are property lines on Google Maps?

Are property lines on Google Maps accurate? No. Google Maps are not that accurate, and you shouldn't rely on them as a source for factual information regarding property lines. Much like a plat map, they only provide a general idea of where property lines exist.

How accurate are property lines?

When closing on the surveyor's own work in new surveys, the minimum accuracy is 1:7,500 or 0.02 metres. When closing on work performed by other surveyors, the minimum accuracy is 1:5,000 or 0.02 metres.