• Community Pool

    The Mountainside Community Pool is a beautiful, barrier-free facility nestled off Mountain Avenue adjacent to Echo Lake Park. Sign up now...

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  • Summer Hours

    Summer Hours for Borough Hall will be in effect from Memorial Day until Labor Day. Monday through Thursday, 8-4:30 PM. Closed for lunch 12-1 PM. Friday 8-1 PM.

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  • Records Available

    Mountainside Borough has opened Construction Department records to the public. You can now search permits, status alerts, online payments, online forms, custom maps and property information. To visit the SDL Portal click below.

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  • Available Now!

    View and Pay your Mountainside Taxes OnlineTo begin, click the link below

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Community Organizations

Get the latest information on your local community organizations' events

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Public Works

Public Works plays an important role in protecting the public's health and safety

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Recreation Pool

Recreation provides a variety of programs and activities for borough residents of all ages

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Engineering Construction & Zoning

Engineering assists and protects the public by means of guidance and inspection.

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Latest News Blog & Twitter

Tax Collection & Finance

The Chief Financial Officer (CFO) is responsible for the administration of the borough’s fiscal affairs. His or her duties include the management of various operating, capital and trust funds; budget preparation; collection of revenues; budgetary accounting; payroll; disbursements; and investment of borough funds.

Pay and View your Mountainside Taxes Online....Click Here

The CFO position is mandated by state law. He or she is appointed to a four-year term and may achieve tenure after serving five consecutive years. He or she is required to be licensed by the state of New Jersey as a Certified Municipal Finance Officer in order to hold the position. In Mountainside, the CFO holds the position of Treasurer, also a licensed position.

Office of the Tax Collector

The Collector of Taxes position is mandated by the state law. He or she is appointed to a four-year term and may achieve tenure after serving five consecutive years. He or she is required to be licensed by the state of New Jersey as a Certified Tax Collector. The collector is responsible for the billing, collection, and recording of all taxes and sewer fees levied upon the properties in Mountainside.

* During first 10 calendar days of a tax period our office is open through lunch.

Property Taxes

Reconciled tax bills are mailed annually in early July.

Due Dates:

1st Quarter February 1st
2nd Quarter May 1st
3rd Quarter August 1st
4th Quarter November 1st
(grace period is during the first 10 calendar days of a tax period)

Commercial Sewer Charges are billed annually (usually mid year).

For information on how to read your tax bill, please refer to the back of your bill under “Explanation of Tax Bill”. 


It is important to note that the municipal taxes are only a portion of Mountainside's property taxpayer's obligation.  There are two other separate entities, Mountainside Board of Education and Union County government that each develop and adopt their own budgets to be funded by your taxes.  The current tax rate for 2017 is 7.473 and the 2017 apportionment is as follows:

                Board of Education:      3.516

                County/Open Space:     2.01

                Local Municipal:            1.823

                Municipal Library:          0.124

If a home is assessed at the average assessment ($164,877), a property would pay $12,321.26 in total taxes for the year ($164,877 x 7.473%).  The breakdown is as follows:

Mountainside 2017 Tax Make-Up
Board of Education 5,797.08
County/County Open Space 3,314.03
Local Municipal 3,005.71
Municipal Library 204.45
TOTAL $12,321.26


Your taxes are broken into 4 quarterly payments.  Do not multiple the 3rd quarter by 4 to determine your taxes since the 1st and 2nd quarterly payments (Feb. 1 and May 1) are half of the prior year's taxes divided equally between the first two quarters.  Any increases or decreases in your yearly tax due to tax rate change or assessment change is shown in the 3rd and 4th quarters (Aug. 1 and Nov. 1).   To determine your yearly taxes, you multiple your assessment which is located on your yearly reconciled tax bill by the tax rate.

In 2017 the average assessed home in Mountainside saw a tax increase of $283.66 broken down below. 

Mountainside 2017 Tax Increase
Board of Education 177.99
County/County Open Space 42.13
Local Municipal 60.18
Municipal Library 3.36
TOTAL $283.66


Payment Options

  • MAIL: Remit check with appropriate stub to mailing address above. If you use online banking, please indicate your BLOCK & LOT in the memo portion and ensure adequate time for delivery as post-mark is not accepted. If you would like a receipt, please enclose a self-addressed & stamped envelope with your payment.
  • In Person: Bring your check/cash with appropriate stub (and entire bill if you would like a receipt) to Borough Hall.
  • Lock Box: Drop your payment with appropriate stub into lock box (located directly outside of the tax office on the 1st floor)

**If you do not know the amount due on any given quarter, please call the office to get the correct amount due before making your payment.

New homeowners who did not receive a tax bill at closing should contact the collector’s office to obtain a copy. The tax office should also be advised in writing of any mailing address changes.



Community Organizations


In strong communities, all generations are valued and work side-by-side on community solutions.


Community Pool

The Mountainside Community Pool is a beautiful, barrier-free facility nestled off Mountain Avenue adjacent to Echo Lake Park.


  • Sun and Fun:
    It offers plenty of sun and swimming for the active set, as well as lots of cool, refreshing shade and a relaxed pace of summer life.
  • World Class Facilities:
    The facility includes a 50-meter Olympic pool, diving tank, zero-depth wading pool, two water slides, basketball courts, baby changing area, men’s and women’s locker rooms, snack bar, picnic grove, benches, and grassy areas to sunbathe

More Information

Community Support

  • Senior Citizens
  • Library

seniorThere are many and varied services available to Senior Citizens in Mountainside.

Most of the programs are county or statewide and not limited to Mountainside residents. In New Jersey, every county has an office on Aging.

These agencies supply information and referral services within their county. Additional information is available from Senior Citizen Coordinator, Kim Moriak at (908) 232-4406.

We have a lot to offer and hope you'll take time to explore our collection. In addition to our online catalog and array of electronic databases, we have a terrific photo gallery that chronicles the last several years of library history. And many people find our schedule of programs and activities a real convenience.

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