Nassau County Level of Assessment Explained
Understand Nassau County full market value, assessed value, and level of assessment—and why you should not compare an assessment number directly with a home sale price.
Reviewed by Chris Ambrosio, CPA · Updated October 7, 2026Why Nassau assessment numbers confuse homeowners
Nassau County can assess property at a fraction of market value. That means the number labeled “assessed value” is not necessarily what the County believes your house would sell for.
Three terms to separate
- Full Market Value: an estimate of the property’s market value.
- Level of Assessment (LOA): the percentage of full market value at which a class of property is assessed.
- Assessed Value: the value produced by applying the relevant assessment level, subject to applicable rules and caps.
Why the level matters in a grievance
If you compare a $700,000 home sale directly with an assessed value of 700, you are comparing two different units. The grievance analysis has to connect market-value evidence to the assessment framework ARC is applying for that filing cycle.
Do not reuse an old multiplier from Facebook or last year’s filing
This is one of the most important practical points we took from studying years of homeowner questions: levels and review practices can change. A shortcut that worked in a prior cycle may be wrong in the next one. Verify the current ARC guidance before relying on any multiplier or ratio.
Official filing dates and procedural references are based on current Nassau County Assessment Review Commission and Department of Assessment materials. County notices and rules control if they change. Educational information is not a guarantee of a reduction.
Reviewed by Chris Ambrosio, CPA
A Certified Public Accountant with over 13 years of financial experience. Chris spent more than six years at a Big Four accounting firm auditing financial services companies, followed by a year in private equity before nearly six years in the real estate industry as a Senior Manager of Accounting. He brings institutional-grade financial analysis to every property tax grievance filing.