Mountainside, NJ property tax appeal: check if you are over-assessed
New Jersey has the highest property taxes in the country, and many Mountainside assessments are out of date. Look up your address to see whether your assessment is above market value, and learn how to appeal before the deadline.
County
Union County
2024 Equalization Ratio
79.83%estimated, verify before filing
Appeal Deadline
April 1
How to know if your Mountainside home is over-assessed
Every property in Mountainside is assessed in New Jersey's MOD-IV system. Because towns rarely reassess every year, your assessment can drift away from what your home would actually sell for. Union County's 2024 equalization ratio is 79.83%, which means assessments in the county run, on average, at that share of true market value. Dividing your assessed value by the ratio gives an implied market value you can compare against your assessment. This ratio is a carried-over estimate pending re-verification, so confirm it before you file.
If your assessment looks high relative to market value and to comparable homes nearby, you may have grounds to appeal. NJ appeals are filed with your County Board of Taxation and are due by April 1 each year (January 15 in a municipality that has just completed a revaluation). Use the free lookup above to get a HIGH / MEDIUM / LOW appeal signal for your specific address.
Mountainside property tax appeal FAQ
What is the property tax appeal deadline in Mountainside, NJ?
The deadline to file a property tax appeal in Mountainside is April 1 of the tax year. In a year when Mountainside has completed a revaluation or reassessment, the deadline moves to January 15. Appeals are filed with your County Board of Taxation on Form A-1.
How do I know if my Mountainside home is over-assessed?
Divide your total assessed value by the county equalization ratio to get an implied market value, then compare it to what your home would realistically sell for and to comparable nearby homes. Union County's 2024 equalization ratio is 79.83%. This value is a carried-over estimate pending re-verification, so confirm it before filing. If your assessment is well above that implied market value, you may be over-assessed.
How do I appeal my property taxes in Mountainside?
File Form A-1 (Petition of Appeal) with the Union County Board of Taxation by April 1, attach 3 to 5 comparable sales or assessments as evidence, serve copies on your municipal assessor and clerk, and attend the hearing. NJ Tax Check can generate a complete appeal evidence packet for your address.
Is it free to check my Mountainside assessment?
Yes. Checking your assessment and appeal signal on NJ Tax Check is free and requires no sign-up. Property tax assessments are public records.
Data sourced from NJ MOD-IV property tax records. Not legal or financial advice. Consult a tax professional before filing an appeal.