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.



Programs for Children

  • Summer Playground
  • Football for K-6th Grade
    • Flag Football
  • Guitar 101
  • Babysitter Training Course (Red Cross)
  • Junior Rock
  • After School Game Room
  • Lacrosse
    • Clinic (Age 7-9)
    • Senior Squirts (Age 5-6)
    • Squirts (Age 4-5)
  • Intro to Basketball Skills
    • Kindergarten
    • First Grade
    • Second Grade
    • Boys Gr. 3-5
    • Girls Gr. 3-5
    • Boys Gr. 6-8
    • Girls Gr. 6-8
    • Bball Boot Camp
    • Basketball Summer Camp

Programs for Adults

  • Wii Bowling League
  • Volleyball
  • Duplicate bridge group
  • Art Classes for Adults with Special Needs
  • High Intensity Interval Training (HIIT)
  • 9/11 Memorial Trip
  • A Christmas Carol
  • Philadelphia Flower Show
  • Total Body Blast
  • Adult Tennis
    • Ladies Nights
  • Yoga
  • Men’s Softball League
  • Women’s Softball League

Community Room

The Community Room at Borough Hall is open for meetings and events. Located on the 2nd Floor, the room includes a main, large meeting room; the Senior Fitness Room, and the Game Room, as well as a storage closet and a bathroom.

The room can accommodate up to 180 people, and may be reserved weekdays and weekends until 11 pm. Scheduling is on a first-come, first-served basis. Municipal purposes, such as elections, board meetings, and scheduled recreation programs, have priority. The room is also available for private rentals. Application for use of the room must be made at least 30 days in advance through the Recreation Office. For reservation information and a copy of the rules and regulations

Game Room

The Game Room contains air hockey, dome hockey, foosball, ping pong, pool, and a variety of board games.

Senior Fitness Room

The Senior Fitness Room provides seniors with an opportunity to improve and maintain a healthy lifestyle through the use of state-of-the-art fitness equipment. Treadmills, an elliptical, a stationary bike, a recumbent bike, a multi-station gym, and dumbbell weights are all available. Free orientation tours are scheduled monthly and are required for new members. The tours include a demonstration of the proper use of equipment. The room is open weekdays from 10:30 am-2:30 pm. Memberships for people ages 55 and above are $60/year or $40/six months. Registration forms are available at the Recreation Department.

Community Pool

Dip, dunk, plunge, and jump into the water at the Mountainside Community Pool. Our beautiful barrier-free outdoor facility features:

  • 50-Meter Olympic pool.
  • Diving tank
  • Two water slides
  • Basketball courts
  • Youth swimming and diving instruction

wadepoolWade Pool

Union County Facilities in Mountainside

  • Echo Lake Park: A beautiful 139-acre park with two lakes. There is boating, skating, and fishing as well as picnic areas, restrooms, dog run, ball fields, playgrounds, and the Union County memorial to September 11, 2001.
  • Summer Music Festival:Featured every Wednesday evening from June through August at Echo Lake Park’s natural amphitheater
  • Watchung Reservation: This incredibly beautiful 2,000-acre wooded reservation is ideal for horseback riding, hiking, and fishing. It features an arboretum, athletic field, bridle trails, cross country ski course, model airplane flying, nature trails, picnic areas, playground, and the deserted village of Feltville.
  • The Watchung Riding Stable: A magnificent state of the art facility located on Summit Lane in Mountainside. It features extensive programs for young and old. Call (908) 654-9404 for information.
  • Trailside Nature and Science Center and Planetarium: Now reopened! Located in Mountainside at Coles Avenue and New Providence Road. The expanded and renovated facility features many programs and special events, both indoor and outdoor.