The assessed value of Napa County vineyards in tax year 2021-2022 accounted for approximately $3.5 billion of the total assessment roll of approximately $45.6 billion. Like all other real property, vineyards are subject to Proposition 13, have base year values and are reassessed on changes of ownership and new construction (new vines or replanting). There are three main components of vineyards that contribute to the total value: the land, the non-living improvements (NLI) including stakes, trellises, irrigation and frost protection and the vines themselves.