Assessment date (October 1)
The date New Jersey uses to value property for taxes: October 1 of the year before the tax year. Your assessment is meant to reflect what your property would sell for on that date.
New Jersey example
Say you are reading your 2027 tax bill. The assessed value on it is based on what a willing, knowledgeable buyer would have paid a willing, knowledgeable seller for your home on October 1, 2026, not what it is worth on the day the bill arrives. Qualified farmland is the exception: it is valued on what it can produce.
Official source
NJ Division of Taxation - General Property Tax Information (How My Property is Valued)
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.