The Mission of the Office of Real Property Services is: "To lead the State's efforts to support local governments in their pursuit of real property tax equity." Appeals must be postmarked no later than 30 days after final assessment roll is filed... Dates vary see: Filing Dates. Initial grievance must be filed with the board of assessment review, upon notice of board of assessment review's determination an appeal can be filed with the small claim assessment review section of the NYS Supreme court. >A successful appeal is based upon first establishing the Market Value of your property. In order to reduce your property taxes you must prove that the value of your property is less than the valuation assigned by your assessing district (according to New York State Law, the Assessment is deemed to be correct, and the burdon of proof, falls on the petitioner-homeowner to prove otherwise). A recent bonafide arms length sale of the subject property is the best evidence. If the property was not recently purchased, or the purchase was not at arms length (as in an inter-family sale, foreclosure or other sale made under conditions of distress), An Appraisal by a New York State Certified Appraiser is the next best type of evidence, which is typically used to prove value of your home throughout the process. To determine if you are over assessed, you can multiply the estimated market value of your property by the residential assessment ratio (RAR-see listings above) that has been establshed for your assessing district. If the result is lower than your property's current assessed value, you may reasonably expect that your assessment be reduced to that amount with proper proof and timely filing in accordance with the guidelines set forth by the New York State Office Of Real Property Services.