Plumber licensing in Montana

Montana reciprocates journeyman licenses from four states — Oregon, Idaho, North Dakota, and South Dakota — and it is application-only, no Montana exam, provided you passed both the written and practical back home, the license is active, and there is no complaint on it. Complete, routine files process in about 30 days by the board's own estimate, and the usual holdup is the certified verification letter from your home board — no letter, no license — so order it before you drive.

Masters get no reciprocity from anywhere: the four-state arrangement is journeyman-only, and a master from any state qualifies and tests like everyone else. From the other states, your license and hours buy experience credit toward qualifying, not an exam waiver — the board approves you, sends an admission letter, and you book the written exams directly with IAPMO.

The application fee is $220 either way. One caution: the reciprocity rule moved into statute in April 2026 and the board's FAQ still quotes the old version, so confirm the current conditions at (406) 444-6880 before you count on the waiver.

Not on an out-of-state card — it has no standing in Montana, and the supervised-work exemption covers apprentices only, not a journeyman waiting on paperwork. But Montana has a genuine fast lane: once the board approves you to sit the exam and you pay $100, it must issue a temporary practice permit — 110 days of legal journeyman work while you wait for your test date.

A master candidate gets the same permit but works at journeyman level on it. Tick the "Temporary Practice Permit" box on the application — the permit does not issue without it. If you are coming in on four-state reciprocity, with no exam to sit, the permit's availability is not established; plan on waiting the roughly 30 days for the license itself, and ask the board.

The journeyman path is 7,500 hours over at least five years, verified in writing by a licensed master or plumbing contractor — or a completed registered apprenticeship, or schooling and industrial-piping practice credited for at most two of the five years. The master path is four years as a licensed journeyman plus three years working with a master or in a supervisory role (the two can overlap), or nine documented years.

Since April 2026 the hands-on practical is gone: journeyman is two written exams at 70% each, master is one, booked with IAPMO after the board's admission letter. Note for pipe travelers: steamfitting, hydronics, and industrial piping count toward journeyman only — never toward master.

Montana does not license apprentices. You work legally under a licensed plumber's supervision, and registration runs through MT Registered Apprenticeship at the Department of Labor & Industry (406-444-4100) — your sponsor initiates it, at no cost to you. A completed registered apprenticeship stands in for the 7,500-hour affidavit when you apply for the journeyman license.

One state license covers every job site in Montana — no city or county worker card was found anywhere, and the license requirement runs statewide. What varies locally is code enforcement and the employer's paperwork (a business license here, a contractor bond there); none of it lands on your card.

The worker license is the gate in Montana. A master may lawfully employ only registered apprentices and Montana-licensed journeymen, so there is no working under somebody else's license — the statute holds the master answerable for trying it. There is no plumbing-contractor competency license at all: the business registers as a construction contractor ($70 and proof of workers' comp), which is the employer's obligation, not yours.