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2025 general tax rate · Union County, NJ
Mountainside property tax rate
Mountainside's 2025 general tax rate is $2.100 per $100 of assessed value. A property assessed at $300,000 owes $6,300.00 for the year. That ranks 425th highest of New Jersey's 564 municipalities, in the lowest quarter, $0.860 per $100 below the $2.960 per $100 state median.
- 1General tax rate $2.100 per $100
- 2Bill on $300,000 assessed $6,300.00
Your Mountainside tax bill
The bill before exemptions and credits. Compare every New Jersey rate.
General rate and effective rate in Mountainside
New Jersey publishes two rates for every municipality. The general tax rate, $2.100 per $100 in Mountainside, is the one applied to the assessed value on the bill: $300,000 assessed owes $6,300.00. The effective tax rate, $1.566 per $100, is "the general property tax adjusted by the municipality's equalization ratio", the rate on market value. Dividing one by the other puts Mountainside's assessments at about 74.57% of market value; the state median is 70.02%.
The effective rate is the fairer comparison between towns. On it Mountainside ranks 469th of 564, against 425th on the general rate, and sits $0.570 below the $2.140 median effective rate. At 74.57%, a $300,000 assessment corresponds to roughly $402,307 of market value.
Mountainside's rate in 2024 and 2025
The general tax rate rose $0.050 per $100 (2.44%) from $2.050 per $100 in 2024, and the same $300,000 assessment owes $150.00 more than at last year's rate. In 2024 Mountainside ranked 436th. The effective rate went from $1.600 to $1.566 per $100 (down 2.13%), and the implied ratio from 78.05% to 74.57%: market values rose faster than assessments.
Tax on common assessed values in Mountainside
| Assessed value | 2025 bill | At the 2024 rate | Versus NJ median rate |
|---|---|---|---|
| $200,000 | $4,200.00 | $4,100.00 | −$1,720.00 |
| $300,000 | $6,300.00 | $6,150.00 | −$2,580.00 |
| $400,000 | $8,400.00 | $8,200.00 | −$3,440.00 |
| $500,000 | $10,500.00 | $10,250.00 | −$4,300.00 |
| $750,000 | $15,750.00 | $15,375.00 | −$6,450.00 |
Each bill is the assessed value divided by 100 and multiplied by $2.100, before exemptions, credits or special charges. These are assessed values, not sale prices: at 74.57% the $300,000 row is a property worth about $402,307. The last column is the difference from the same assessment at the $2.960 per $100 state median.
How Mountainside compares in Union County and New Jersey
Among the 21 municipalities in Union County, Mountainside ranks 20th highest; the county median is $5.242 per $100, so Mountainside sits $3.140 per $100 below it. The next higher rate in the county is Clark Township at $2.269, and the next lower is Elizabeth at $2.017. Statewide, 24% of municipalities have a lower general tax rate than Mountainside.
Outside Union County, the closest rates are Washington Township (Burlington County) ($2.103, Burlington), Chatham Township ($2.104, Morris), Manville ($2.110, Somerset), Matawan ($2.087, Monmouth). Because towns assess at different shares of market value, the effective rate is the better guide to what a house of a given price pays.
Appealing a Mountainside assessment
New Jersey appeals go to the Union County Board of Taxation. The petition is due April 1, or May 1 in a year when Mountainside implemented a municipal-wide revaluation or reassessment (NJ Division of Taxation). Property assessed above $1,000,000 may go directly to the Tax Court, and a County Board judgment can be appealed to the Tax Court within 45 days. The Board tests the assessment against the common level range: the average ratio plus or minus 15%. Using the 74.57% ratio implied by the state's two rates, that range runs from about 63.38% to 85.76% of market value; the Director's official average ratio for Mountainside, which the County Board applies, can differ slightly.
The New Jersey appeal page sets out each step with its source and the ratio arithmetic. This is a summary of the published procedure, not legal advice.
Mountainside property tax questions
What is the property tax rate in Mountainside, NJ?
Mountainside's 2025 general tax rate is $2.100 per $100 of assessed value; its effective rate, on market value, is $1.566 per $100. Source: New Jersey Division of Taxation.
How much is the property tax on a $300,000 assessment in Mountainside?
$300,000 ÷ 100 × $2.100 = $6,300.00 a year, before exemptions and credits. At the 2024 rate the same assessment owed $6,150.00.
Is Mountainside's tax rate high for New Jersey?
It ranks 425th highest of 564, in the lowest quarter of New Jersey municipalities; the median is $2.960 per $100. On the effective rate, which allows for different assessment levels, it ranks 469th.
How do I appeal a Mountainside property assessment?
Petition to the County Board of Taxation: by April 1 (May 1 after a municipal-wide revaluation) (NJ Division of Taxation; Guide to Tax Appeal Hearings). Then: county board hearing and judgment (Set by the County Board); appeal to the tax court (Within 45 days of the County Board's judgment).
Source: New Jersey Division of Taxation, 2025 General Tax Rates (general and effective tax rates by county and municipality); prior year from the 2024 General Tax Rates. Appeal steps: NJ Division of Taxation, Assessment and Appeals (updated August 15, 2025); NJ Division of Taxation, A Guide to Tax Appeal Hearings (revised 2022). Last checked October 21, 2026. This page explains published figures; it is not tax or legal advice.