How to Start a Plumbing Business in Maine

Master License First, Business Second

You can't legally operate an independent plumbing contracting business in Maine without a Master Plumber license. Journeymen can perform installations and repairs under a Master Plumber's direction, and may do minor plumbing repair work as a regular part-time occupation, but only a Master can pull municipal permits and serve as the license of record on projects.

Maine does not have a statewide general contractor license — LD 1226, which would have created one, died on adjournment on April 29, 2026. That means there's no separate statewide "contractor license" to obtain, although municipal requirements still apply. Your Master Plumber license is your trade credential; the business setup is a separate administrative layer.

Register Your Business Entity

Register with the Maine Secretary of State, Bureau of Corporations, Elections, and Commissions. Your entity type — LLC, S-Corporation, or sole proprietorship with a DBA — determines your personal liability exposure and tax treatment. If you're operating under any name other than your own legal name, you'll need a DBA registration with your local municipality as well.

Set Up Tax Accounts

Register with Maine Revenue Services for state income withholding and any applicable sales tax obligations. Obtain a federal Employer Identification Number (EIN) from the IRS as applicable to your entity and tax accounts.

Get Insured

Workers' Compensation is mandatory for any Maine construction business with one or more employees — full-time, part-time, or seasonal. Self-employed Master Plumbers with no employees are exempt from the state Workers' Comp mandate, but most general contractors and commercial clients require proof of WC coverage as a subcontracting condition. Skipping it limits your market.

General liability insurance isn't state-mandated for plumbing licensees, but it's practically mandatory. Local code enforcement offices frequently require proof of coverage before issuing municipal permits. Coverage levels vary, but $100,000 per occurrence is a common municipal minimum — many commercial projects require $500,000 to $1,000,000.

Written Contract Requirements

Under Title 10, Section 1487, any residential construction or improvement project exceeding $3,000 in total materials and labor must have a signed, written contract. The contract must include the scope of work, payment schedule, and warranty disclosures. Down payments are capped at one-third of the total contract price. Violating these requirements is treated as an unfair trade practice under Maine consumer protection law.

This threshold applies to every plumbing contractor working on residential projects. A $4,000 bathroom remodel needs a signed contract just as much as a $40,000 whole-house repipe.

Pulling Your First Permits

With your Master license active, your business registered, and your insurance in place, you're ready to pull municipal plumbing permits. Submit the HHE-211 Internal Plumbing Permit Application to the local code enforcement office or LPI. Permit processes and fees vary by municipality — Portland uses an online CSS portal, Auburn uses SmartGov, and small towns may have a plumbing inspector available only a few hours per month.

The Maine Plumber License Guide covers the full sequence from Master license activation through business formation, insurance requirements, and municipal permitting.

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