And don't forget to think of it this way, if the houses assessed value is much lower than it's market value, that homes owner is actually paying LESS in taxes than they should be. This is not a suggestion to pay any asking price because it's above assessed value... You need to ignore assessed value, and pay attention to market value.
Tax appraisals, as the others have pointed out, are done by your county auditor's staff. In my county there are at least four appraisers each assigned to a different area and it is unbelievable how different their appraisals are when compared to the selling price of a home (did a lot of research in preparation of appealing my homes assessment). A realtor can helpt you get with recent sales that have occured in the areas you are looking at--but the best method is to visit the types of homes you are interested in --a lot of homes--and through experience become your own appraisor. When you find a home for for a price that your experience tells you is a good value, hope that the tax appraisal is low, who wants to pay high taxes?
Market Value and Tax assessment can vary tremendously frojm community to community. Tax assessment is just that - it is used to calculate property taxes, and since the tax rate differs from town to town and year to year.
If you are getting frustrated trying to make sense of this, you really should find yourself a qualified Buyer Agent who can help you make comparisons between properties in a town or between towns. A buyer Agent represents you and can help you evaluate the market sublties not always obvious from such data as assessments.
Good luck - I'd be happy to talk with you about this more if you are interested.
Accredited Buyer Representative