Plumbing Contractor License in New Hampshire: Requirements, Qualifier, Bond and Exams

Yes — statewide.

New Hampshire licenses plumbers at the apprentice, journeyman and master levels under RSA 153:27-38, and the state's business-entity obligation reaches plumbing companies directly: there is no license class called plumbing contractor, and the board's Mec 307.05 rule says no business shall perform fuel gas fitting, plumbing, hearth system installing or servicing, or domestic appliance installing or servicing without a business entity license.

The old plumbing law, RSA 329-A, was repealed effective July 1, 2013, so a source still citing it is out of date.

A licensed business entity may apply for and receive a permit from any municipality in the state, and our research found no monetary job threshold in RSA 153 or the board's rules as we read them — the license turns on the trade practiced, not the size of the job.

The Mechanical Licensing Board, part of the Office of Professional Licensure and Certification (OPLC), issues it.

The business license a plumbing company takes is the Mechanical Business Entity license, and it covers plumbing, fuel gas fitting, hearth and domestic appliance businesses — the rules define the entity by the trade it is engaged in, quoted below from Mec 307.

A company whose work reaches water treatment has a separate class: the board issues a Plumber Water Treatment Business license, also $275, and it certifies water treatment technicians individually under RSA 153:27 and the Mec 800 rules.

A Mechanical Business Entity must employ at least one corporate officer, or responsible managing employee, who currently holds the matching New Hampshire license — for a plumbing business, the master plumber license.

The state's law reaches the business through that individual license: a master plumber is defined as the person or business that employs plumbers or does plumbing as a business, and a journeyman plumber works under a master's direction.

The road to master runs through journeyman — the in-state route needs an apprenticeship completion certificate, at least 600 hours of plumbing education and at least 8,000 hours of on-the-job experience — then at least 6 months holding the New Hampshire journeyman license and a 75% pass on the master exam.

For the business license, none.

New Hampshire can issue a mechanical business entity license without an examination or continuing education, and no business-and-law exam requirement exists for it.

The exams sit on the individuals behind the business: your qualifier passes the master plumber exam with at least 75%, and a journeyman licensed in another state can qualify for the New Hampshire journeyman license by passing the journeyman exam with at least 70%.

Since May 12, 2025, the state's plumbing examination is proctored by ProV (Professional Credential Verification); our research did not capture the plumbing exam's format or code edition, so check the ProV candidate bulletin before your qualifier books.

We also did not confirm a separate state medical-gas or backflow-tester license under the board: backflow devices appear among the plumbing exam topics, and New Hampshire DES may certify backflow testers separately — ask the board where specialty work lands.

New Hampshire sets no surety bond for this license and no minimum insurance amount — neither RSA 153:29-a nor the board's Mec 307 rules establish one, and those two sources are what this reading rests on.

What the state does require is documentation at both ends of the license: all business entities shall provide proof of good standing with the Secretary of State and proof of liability insurance before the license is issued and again at every renewal.

The practical task is to carry coverage and produce the certificate, not to hit a state dollar floor.

The Mechanical Business Entity license costs $275 to apply for and $275 to renew as of September 29, 2026, and a sole owner with no employees is exempt from the fee.

The entity license renews every 2 years, with the rules setting its expiry at the last day of January, biennially.

The qualifier's individual license carries its own fees, charged at application and again at each renewal: $330 for a master plumber, $198 for a journeyman and $88 for an apprentice as of the same date.

Individual mechanical licenses expire every 2 years, and each endorsement needs at least 6 hours of board-approved continuing education per 2-year cycle.

Calendar the renewal: an individual plumbing license holder who renews 365 or more days late is treated as a new applicant and must re-test.

And take fees from the board's current fee page — older application packets still circulate with different amounts.

For individuals, yes — under New Hampshire's 2023 universal-recognition law (HB 594, RSA 310:17), OPLC's reciprocity page lists 34 qualifying jurisdictions for journeyman plumbers and 9 for master plumbers: Colorado, Connecticut, Delaware, Florida, Louisiana, Michigan, Rhode Island, Utah and Vermont.

A candidate qualifier holding a master plumber license from a state on that list is the case to take to OPLC first — confirm the current list with OPLC before you rely on it.

The testing route is open regardless: a journeyman licensed in another state can qualify for the New Hampshire journeyman license by passing the NH journeyman exam with at least 70%.

For the business entity license itself, our research did not establish a reciprocity route — ask the board, and plan on New Hampshire's own requirements for the business.

Two notice rules apply, and the first stops work.

If the business loses its licensed officer or responsible managing employee, it must notify the board within 30 days, and it may not act as a fuel gas fitter or plumber until some other officer, member or designee has obtained a licensed fuel gas fitter or master plumber as the responsible managing employee — the rule is quoted below.

In practice, a plumbing company's plumbing work stops until a replacement master plumber is in place, so line up a successor before your qualifier departs.

The second rule reaches the crew: a plumbing business must also give the board notice within 30 days when a plumbing apprentice or gas trainee severs employment.

Two boundary rules decide which jobs the plumbing license actually reaches.

The state's legal definition of plumbing stops at the first fitting beyond the foundation wall of the building or 5 feet of pipe from the building.

And the plumbing license does not apply to plumbing performed in connection with installing heating, cooling, air conditioning or domestic water heating systems — solar, oil, gas or electric — or to water treatment and pool work, though code, permit and inspection rules still apply.

Fuel gas fitting is a separate obligation: no business may perform it without a business entity license, and a licensed plumber can add a fuel gas piping installer license by completing 60 hours of approved training.