The local county will review and re-evaluate the home tax value maybe every now and then (might as long as 5 to 6 years) just to make sure the property tax they charged is on the fair market side. This value might reflect some degree of the home value if the local real estate market in your area is relatively stable in the past few years. But if you need a detailed analysis report about the current fair market value of your home you need always contact your realtor to run a CMA (comparative market analysis) report.
Fair Market Value for Tax purposes is based on mechanical functions and as stated below can be different from what percieved value the home has to the buyer. If you want to get top value for your home you must listen to your Realtor and the professionals that surround them. Choose an agent based on honest feedback and advise.
If you are buying a home then utilize your Realtor as a "Buyers Agent" and allow them to assist you with the homes value.
E will sell for at a given point in time, you really need to look at comparable home sales. If you would like help, I'm happy to help! I grew up in Little Chute and know the area very well. You can call me at 920-740-3599 if you'd like. Either way, a Realtor is your best bet for a price opinion instead of the tax assessor :)