In the town of Amherst NY right now, the assessed value is only at 92% of market value. The Town of Cheektowaga is only 62% of market value. It is even harder to determine what that city, town or municipality considers a property's Fair Market Value to be. So many towns do not review the assessments every year, even though the State pays them to (at least New York State) and every two years they are supposed to re-assess, up or down depending on the market. When the Assessor does a reassessment review, all recorded sales are taken into consideration and may become the new assessed value of a particular property and also the similar homes surrounding it. There are other sales that are not supposed to be used as market value and those are foreclosures and sales to family members. When builders close on a home, the sale price sometimes is not the WHOLE price of the house. Upgrades may have been paid for by the buyer on the side and the total cost at closing could be significantly less than what the buyer actually has invested in a house. Legal or not, it still is happens. The assessor however, does not have to go with the recorded sale price and may put their own figure on it based on similar home sales in the neighborhood. Then, it is up to the homeowner to prove that it is worth less, which may mean having them come in the home. The majority of reasons an assessor's Fair Market Value may be lower than it should be is the failure of many homeowners to get the proper permits when making home improvements and adding on (including, pools, fences, family rooms, garages etc.)
So, the answer to your question is this: If you buy a home for $200,000 and the assessed value is at full value assessment at the time of closing, most likely within 12-18 months, your assessment will be adjusted accordingly. Then, your taxes will probably increase.
MJ Peterson Real Estate