Karen, as others have stated, using such numbers found in the tax assessors data base takes you down the slippery slope of irrelevance. I do keep track of these numbers and find market value can range from 0.6 to 1.6 of assessed value. I will suggest there are community attributes that will suggest which communities will have assessed values closest to market value.
Without an intimate knowledge of the communities that will allow you to calibrate properly, you are going to be just as accurate taking the random numbers generated by Zillow and Trulia.
Now, be advised, there are many enterprises (Bank of America) who will actually use Zillow as a basis for evaluation of the value of a house. If you want to be considered as competent as Bank of America, then the tax assessed value, Zestimates. Evaluations and the gray beard at the end of the street are all legitimate sources.
If, however, you are on the verge of making a real estate decision, you would be well advised to rely on the knowledge and experience of those who help in the sale and purchase of dozens of homes every year. They are just a phone call away.
Best of Success,
Annette Lawrence, Broker/Associate
Palm Harbor, FL
Take a look at the "Market In A Minute" (MIAM) reports I've posted on Trulia. The data revealed are the indicators regarding whether the tax assessed value has any relevant relationship to market value. But, with a MIAM report, you have all the data you need anyway.... more