Of all the property tax terminology unique to Long Island, "Level of Assessment" is the most asked-about on r/longisland. Short version: Nassau assesses every residential property at 10% of market value, but levies tax against the full market value. Long version below.
Historically, Nassau used a "fractional assessment" approach — assessing properties at far less than market value (around 1% in some cycles, up to 4% in others). This wasn't about tax dodging; it was an administrative artifact dating back decades. The actual tax rate was correspondingly higher to make the math work.
In 2020, the County standardized the residential Class 1 LoA at 10% — meaning a $500,000 home is assessed at $50,000, and the tax rate is applied to that $50,000 figure (rather than $500,000). The dollar amount of tax owed is essentially the same as if assessed at 100% and a lower rate were applied.
It's economically equivalent. It's just presentation — and it confuses everyone.
If you want to see what the County thinks your home is worth:
Implied market value = assessed value ÷ level of assessment
So if your Nassau assessed value is $52,000 and the LoA is 10%:
$52,000 ÷ 0.10 = $520,000 implied market value
This is the figure to compare against actual sale prices in your neighborhood. If recent comparable homes sold for $475,000-$500,000, you have a case to grieve down.
Three related terms that all describe assessment-to-market-value ratios:
For grievance purposes, NY State law lets you use the lower of LoA, Equalization Rate, or RAR. So if Nassau's declared LoA is 10% but the RAR (based on recent sales) suggests assessments are actually running at 9.2%, you can grieve using 9.2% — which lowers your implied market value calculation and strengthens your case.
No, not directly. The LoA only affects the presentation of your assessment. The actual tax owed is the same whether your home is assessed at 10% × $500k × $X rate or at 100% × $500k × $X/10 rate. What matters is whether the implied market value is accurate.
For Class 1 (1-3 family residential), Nassau's LoA has been 10% since the 2020-21 tax cycle. The LoA can change with each annual reassessment cycle, but has been stable.
Suffolk towns generally assess at 100% of market value (full value). Some towns use locally-set LoAs in special cases, but the standard approach is "full value" — your assessed value is the assessor's estimate of what your home would sell for.
No. A low assessed value relative to market is good — it means a lower tax bill. The concern is when assessed value is too high relative to your actual market value. That's when you grieve.
Grievance deadlines, STAR limit updates, new exemption laws. One short email, only when something actionable happens. Unsubscribe in one click.
Subscribe →Last verified: 2026-05-11. Tax rules change; we re-verify each page quarterly.
Estimates and educational content only — not legal, tax, or financial advice. Verify with your county or town receiver, an attorney, or a CPA before making financial decisions.