Sales tax and bookkeeping for HVAC, plumbing and electrical contractors in New Jersey

New Jersey treats plumbers, electricians and HVAC installers as contractors, and every job falls into one of three buckets. A capital improvement adds to the value or useful life of the building and is permanently attached. A repair restores something to working condition without adding value. A maintenance service keeps property in its existing condition. Exempt capital improvements carry no tax on the customer's bill. Repairs and maintenance are taxed, and the tax goes on your labor.

• Exempt capital improvements the state lists for these trades: new heating system, new central air conditioner, new hot water heater, rewiring, new electrical outlets, new bathroom and kitchen fixtures, attic ventilation fan.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Repairs the state lists: fixing faulty plumbing and fixing faulty electrical outlets. Repairs are taxable, and the customer pays tax on labor.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Scale can flip the answer. Replacing a few loose tiles or part of a leaky roof is a repair; replacing all of it with upgraded materials is an exempt capital improvement.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Some capital improvements are taxable anyway: hard-wired security, burglar or fire systems, carpeting and other flooring, landscaping, and permanently affixed signs. Electricians wiring alarm systems charge tax on that work.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Residential heating is a special case. Maintaining or repairing a heating system in a building of three families or fewer is exempt on parts and labor, with no certificate needed. So is cleaning and servicing residential furnaces, stoves and chimneys.

  Source: NJ Division of Taxation, ANJ-8 Air Conditioning, Heating, Refrigeration

• Air conditioning repair is always taxable labor, even on a home. Residential heating service contracts are exempt; every other maintenance contract, including residential AC plans and all commercial plans, is taxable to the customer.

  Source: NJ Division of Taxation, ANJ-8 Air Conditioning, Heating, Refrigeration

• Window and through-the-wall units the owner can remove are not capital improvements. Both the unit and the installation are taxable.

  Source: NJ Division of Taxation, ANJ-8 Air Conditioning, Heating, Refrigeration

• Commercial heating: labor to maintain, service or repair a central heating system in a non-residential building, or one with four or more families, is taxable to the owner.

  Source: NJ Division of Taxation, ANJ-8 Air Conditioning, Heating, Refrigeration

If a job does not fit cleanly, the state says you may use its federal income tax treatment as a guide, or describe the work to the Division of Taxation and ask.

New Jersey contractors always pay sales tax on materials and supplies at the time of purchase, including air conditioning, heating and refrigeration units. There is no resale option for construction materials. That tax belongs in your job cost, not on the customer's invoice.

• On a taxable repair, the only amount you can leave out of the taxable total is the separately stated pass-through of the actual cost of materials. Bill one lump sum and the entire receipt is taxable, including materials you already paid tax on.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• A customer should never be charged sales tax on parts for a central heating system installed by a contractor. You pay tax on those parts when you buy them.

  Source: NJ Division of Taxation, ANJ-8 Air Conditioning, Heating, Refrigeration

• Materials bought out of state or online with no tax, or at a lower rate, owe New Jersey use tax on the difference. The state's own example: lumber bought in a 4% state owes 2.625% use tax on a New Jersey job.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Sales tax is reported on the accrual basis: in the period the sale took place, whether or not the customer has paid.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Jobs for exempt organizations with an ST-5 (government, churches, charities, volunteer fire companies) carry no tax on materials or labor. Use Form ST-13 with your supplier.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

• Work for a qualified Urban Enterprise Zone business at its zone property: buy materials tax free with Form UZ-4 and charge no tax on labor, up to $100,000 of purchases per business per year across all its contractors.

  Source: NJ Division of Taxation, S&U-3 Contractors and New Jersey Taxes

New Jersey licenses the three trades at state level through boards under the Division of Consumer Affairs. Licence fees and renewals are business expenses worth tracking on their own line, because the cycles differ by trade.

• Master plumbers renew every two years with the State Board of Examiners of Master Plumbers. Renewal fee $160, late fee $50, reinstatement $150. A renewal notice goes out at least 60 days before expiry, with a 30-day late window.

  Source: N.J.A.C. 13:32-2.6, master plumber renewal

• Electrical contractors renew every three years with the Board of Examiners of Electrical Contractors: $225 for the licence and $150 for the business permit, $50 late fee within 30 days.

  Source: N.J.A.C. 13:31-1.6, electrical contractor fees

• Master HVACR contractors renew every two years: $160, late fee $50, reinstatement $150. Five continuing education credits each cycle, first renewal exempt.

  Source: N.J.A.C. 13:32A-6.1, HVACR fees

• A licensed master plumber working on heating systems, piping and gas lines within scope, or a licensed electrical contractor installing electric resistance heating and small ventilation equipment, does not need a second HVACR licence.

  Source: N.J.A.C. 13:32A-1.1, HVACR licence exemptions

• Home improvement contractor registration runs April 1 to March 31 each year: $110 to register, $90 to renew, $25 late. Licensed electrical contractors and master plumbers acting within their trade are exempt from it.

  Source: N.J.A.C. 13:45A-17.5, home improvement registration period

• Since 2024 a registered home improvement contractor needs workers' compensation insurance, general liability of at least $500,000 per occurrence, and a bond or other security of $10,000, $25,000 or $50,000 depending on contract size.

  Source: NJ Consumer Affairs, contractor registration changes under P.L. 2023, c. 237

New Jersey winters drive the trade. Furnace and boiler calls run roughly November through March, air conditioning emergencies June through August, and the spring and fall shoulders are when planned replacements and tune-ups happen. For bookkeeping that means two cash peaks and two troughs, so each month should be compared with the same month last year.

• In 2024 New Jersey had 3,501 plumbing, heating and air conditioning contractor establishments employing 30,290 people at average pay of $87,929, and 2,766 electrical contractor establishments employing 25,051 at average pay of $90,693.

  Source: BLS Quarterly Census of Employment and Wages, New Jersey 2024

• Roughly three quarters of plumbing and HVAC establishments (2,610 of 3,501) and most electrical ones (1,760 of 2,766) are residential-focused, which is where the heating exemption and the ST-8 matter most.

  Source: BLS Quarterly Census of Employment and Wages, New Jersey 2024

1. 1A new furnace with no ST-8 on fileThe job was a real capital improvement, but nobody collected the owner's signed Form ST-8. At audit the state treats it as taxable labor. We check that every exempt job in QuickBooks has a certificate attached.
2. 2Lump-sum repair invoicesA taxable repair billed as one price is taxed on the whole amount, including the parts you already paid tax on. Materials have to be a separate line at actual cost. We set the invoice templates up that way.
3. 3Taxing heating parts, or not taxing AC plansCustomers should never be charged tax on central heating parts, while every air conditioning service plan and every commercial plan is taxable. Shops often have both backwards in their item list.