On its own, no.
From the 2010 Guidance:
An institution may use a TAV in developing an evaluation when it can demonstrate that a valid correlation exists between the tax assessment data and the market value. In using a TAV to develop an evaluation, an institution should:
Determine and document how the tax jurisdiction calculates the TAV and how frequently property revaluations occur.
Perform an analysis to determine the relationship between the TAV and the property market values for properties within a tax jurisdiction.
Test and document how closely TAVs correlate to market value based on contemporaneous sales at the time of assessment and revalidate whether the correlation remains stable as of the effective date of the evaluation.
If you are going to use an assessor's value only, then you follow the above. Normally the assessors value is just one piece of your valuation. If you are looking to create your own valuations, I would review the 2010 Guidance with particular attention to the sections Evaluation Development and Evaluation Content.
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