What I would do is calculate the most recent sales of similar houses and match each sale with its tax assessment. If the column of recent sales and column of tax assessment differ, divide one into the other and that becomes a ratio on one to the other. Apply that ratio to any one house and you can answer your question. However, an individual house may have extra updates or improvements or worse, be in much worse condiditon that an average house of its age, and these facts alter the expected sales price.
Take a look at some of the market trends in Nutley: http://www.trulia.com/real_estate/Nutley-New_Jersey/market-trends/
Why do you feel the homes are selling higher than the assessed value and why do you think this is happening?
That's a really good observation, I am looking forward to learning more from members of the Trulia Voices community.
Ali, Community Manager
If the assessed values are updated and current, homes should always sell for prices that exceed the assessed numbers.