In an update year, assessments as of April 1st should be fairly representative of market value. Because sales are based on emotional likes and dislikes of buyers, there is no one right number, but rather a range of numbers depending on the negations and motivations of the buyers and seller involved in a transaction. The industry standard indicates that plus or minus 10% is reasonable because an opinion of value is subjective and will vary by this amount.
When there is a decline in the real estate market, taxpayers may see that their assessment is higher than what they could expect to sell their property for (market value). That does not invalidate the towns assessment of your property when they account for the local assessment to sales ratio because every year the New Hampshire Department of Revenue Administration (DRA) calculates an equalization ratio. This ratio represents the difference between the assessment and the market transactions (sales). Here is an example:
In the town where you live in New Hampshire, the DRA published the an equalization ratio of 1.15% as of 4/1/2017. The assessment on your home is currently $300,000. Homes similar to yours are currently selling for $250,000. You may think that you are being over assessed, but this is where the equalization ratio comes into play.
To determine the market value of your home you would take the assessment of $300,000 and divide it by the ratio of 1.15% which gives you an indicated market value of $260,870. Although this number may be higher than the $250,000 sale price, it is considered fair and equitable so long as it falls within the 10% allowance.
 So long as all properties are being assesses similarly, the assessments, even if they are higher than current market value are fair and equitable because everyone is being treated the same. The real estate market is constantly fluctuating which makes comparisons of assessment and sales very difficult. The Form PA-34 that you complete at closing is one of the tools that the DRA uses in determining the equalization ratio.