Massachusetts Contractor Taxes and Licensing: What Trades Need to Know

Massachusetts treats contractors who build, remodel or repair real property as the consumers of their materials: you pay the 6.25% sales or use tax when you buy, and you don't charge sales tax on the job. Residential work usually needs two separate credentials: a Home Improvement Contractor registration and a Construction Supervisor License.

What makes Massachusetts different for contractors?

Two things trip up trades in Massachusetts. First, the state splits residential credentials between two agencies: the Office of Consumer Affairs and Business Regulation (OCABR) runs Home Improvement Contractor (HIC) registration, and the Office of Public Safety and Inspections runs the Construction Supervisor License (CSL). OCABR says plainly that the two "are not interchangeable." Second, the state has a flat income tax with a 4% surtax on very high incomes, which matters if you sell a business or have a big year.

Out-of-state crews face their own rules. The Department of Revenue (DOR) says out-of-state contractors must register through MassTaxConnect, post a bond or surety deposit on projects valued at $20,000 or more (materials included), and hand the customer a DOR Certificate of Compliance before the job ends. Customers who skip that step can be personally liable for tax on the materials.

Is contractor labor taxable in Massachusetts?

Generally no. DOR's guide for plumbers says that when trades construct, alter, improve, remodel or repair real property, they are "the consumers of tangible personal property (material)" and pay sales or use tax on the full price of materials at purchase. The customer isn't charged sales tax on that contract. The sales and use tax rate is 6.25%, per DOR's tax rates page.

The exception is when you act as a vendor. DOR says that happens when you sell material and simply install a complete unit of standard equipment without substantial fabrication. Its examples:

• Replacing a faucet with the price split out: tax is due on the faucet; the labor charge isn't taxed.
• Same job, one combined price: the whole charge is taxable if the faucet is more than 10% of the total.
• Fixing a leak with stock parts, billed lump sum: no tax on the charge; you paid tax on the parts as the consumer.
• Water heater sold and installed: tax on the heater; installation isn't taxed if it's separately stated.

So in Massachusetts the deciding question isn't repair vs. improvement, it's whether you're doing a construction contract or selling a unit and hooking it up. How you write the invoice matters. For the bigger picture, see sales tax on labor vs. materials.

Do Massachusetts contractors pay tax on materials, and which forms apply?

Yes. DOR says trades acting as contractors "do not provide resale certificates" for material going into taxable projects. The certificates you'll see:

• Form ST-4, Sales Tax Resale Certificate: only when you act as a vendor and buy material to resell to the customer.
• Form ST-5C, Contractor's Sales Tax Exempt Purchase Certificate: for building materials on projects for government bodies or 501(c)(3) organizations under G.L. c. 64H, § 6(f). A 501(c)(3) customer must also give you its Form ST-2.
• Form ST-12, Exempt Use Certificate: for material used in an exempt manner, such as in a qualifying manufacturing plant. You must prove the exempt use on audit or owe the tax.

Tools are different. DOR says you're the consumer of tools you buy or rent and pay tax on them, and tools bought for an exempt job are still taxable. Rentals tied to an exempt customer's contract are exempt.

Use tax catches materials bought tax-free. DOR says a 6.25% use tax is due on the full price of building materials brought in from a state without a use tax, "such as New Hampshire," or from another country. Buy in a state with a lower rate and you owe the difference. DOR's example: pay 5.5% in Maine, owe 0.75% to Massachusetts. More on this in use tax for contractors, and compare the rules in New Hampshire and Rhode Island.

Do you need a contractor license in Massachusetts?

For most residential work, yes. OCABR says contractors who solicit, bid on or perform work on an existing, owner-occupied, non-commercial property with one to four units must register as an HIC. The CSL is about who supervises construction under the state building code: for 1- and 2-family homes, a licensed construction supervisor or registered design professional must oversee the work. OCABR's chart shows decks, roofing, siding, windows and structural carpentry needing both. Exterior painting needs only an HIC registration.

Local rules sit on top of this. OPSI says to "always check with the municipal building official" in the city or town for added licensing requirements, and building permits are pulled locally. It also notes that Massachusetts doesn't recognize out-of-state contractor licenses. Your HIC number must appear on contracts, permits and ads. More background: contractor license basics.

How is a contracting business taxed on income in Massachusetts?

DOR's tax rates page lists a flat 5.00% personal income tax on wages and most other income. For tax year 2026, an extra 4% surtax applies to income over $1,107,750 (it was $1,083,150 for 2025). Sole proprietors and single-member LLCs pay this on their business profit through their personal return. S corporation and partnership income flows through to owners the same way.

• Pass-through entity excise: S corps and partnerships can elect the chapter 63D excise at 5% of qualified members' income. Starting with tax years on or after January 1, 2026, they can also elect a chapter 63E excise at 4% of income over the surtax threshold. Members get a credit equal to 90% of their share. The election is made on Form 63-ELT and is irrevocable for that year. Single-member LLCs that are disregarded can't elect.
• Corporate excise: business corporations pay 8.0% of net income plus $2.60 per $1,000 of tangible property or net worth, with a $456 minimum. S corporations owe the same $456 minimum, with an entity-level tax only above $6 million in total receipts.
• Estimated payments: DOR says you must pay quarterly if you expect more than $400 of tax on income without withholding. For 2026 the installments were due April 15, June 16 and September 15, 2026, and January 15, 2027.

Plan for both federal and state estimates. See quarterly estimated taxes for contractors or run the numbers in the quarterly estimated tax calculator.

Who needs workers' comp in Massachusetts?

Every employer. The Department of Industrial Accidents (DIA) says all employers must carry workers' comp for their employees "no matter the number of hours worked or the number of employees." Sole proprietors, LLC members and LLP partners don't have to cover themselves, but their employees must be covered. Corporate officers who own at least 25% can request an exemption.

Enforcement is fast. The DIA issues stop work orders with minimum fines of $100 a day, weekends included, and uninsured employers can be barred from public contracts for three years. Out-of-state employers must cover workers on Massachusetts jobs too. See workers' compensation for contractors.