Net valuation taxable
The total assessed value of all taxable property in a town, after partial exemptions and abatements are subtracted. It is the base that the town's general tax rate is applied to.
New Jersey example
Union County's 2025 Abstract of Ratables lists Berkeley Heights' net valuation taxable at $1,862,695,565, with a general tax rate of 4.401 per $100 of assessed value. Say a home there was assessed at $500,000: $500,000 x 4.401 / 100 = $22,005 in taxes for the year.
Official source
This is a plain-English summary. Rules and dollar amounts change, so check the official source or a professional before you file or sign anything.