A Triennial Update is a review of valid sales over the period of 3 years since the last reappraisal. The sales data is analyzed for trends in the market and values are equalized based on sales factors specific to each neighborhood. Changes in value will vary between neighborhoods. Neighborhood areas for valuing purposes are defined by like housing, type, age and size. This is designed to update market values and therefore update assessed values of properties to tax purposes. Triennials occur 3 years after the last reappraisal.