Most states require a license to do plumbing work — but whose license it is varies more than you'd expect.
Twenty-four jurisdictions run an apprentice → journeyman → master ladder, seven leave plumbing licensing to cities and counties, and in Arizona and California the law exempts an employee paid wages as their sole compensation.
In every state our research verified, plumbing for the public happens under some license.
The variable is whether it has to be yours.
When you can work without a license: apprentices, helpers and wage employees
You can work in plumbing without holding a license yourself.
The states that regulate individual plumbers all build in a legal entry rung, and the states that don't license individuals still let you work under someone else's.
What none of them allow is contracting on your own without the required license.
The legal routes in:
- Registered apprentice or trainee. In the 24 jurisdictions whose plumbing license runs apprentice → journeyman → master, registration is the legal way to start — you work under a licensed journeyman or master while your hours count toward a license of your own.
- Unlicensed under a master, no registration. Delaware licenses only the master plumber: apprentices and journeymen work unlicensed under a master who employs them or works full time for the same business.
- W-2 employee of a licensed firm. North Carolina has no statewide journeyman or apprentice plumber license; unlicensed workers may work as W-2 employees of a licensed firm.
- Wage employee in a contractor-license state. Arizona's contractor licensing law exempts anyone who does regulated work as an employee with wages as their sole compensation (A.R.S. §32-1121(A)(11)), so employed plumbers need no ROC license of their own. California's law says the same (Bus. & Prof. Code §7053): the CSLB license is the employer's, not yours.
Registration, where it exists, is deliberately cheap.
Louisiana licenses plumbers statewide through the State Plumbing Board of Louisiana, and every unlicensed person doing plumbing or gas fitting must register as an apprentice, work for a master company and be supervised by a journeyman or master.
Minnesota's entry credential is the registered unlicensed plumber — no experience needed, a $14 fee, renewed every June 30 with 2 hours of code CE — and the holder must be a W-2 employee of a licensed plumbing contractor or registered plumbing employer.
Minnesota is equally explicit about the supervision that follows: only DLI-licensed plumbers, DLI-registered unlicensed plumbers, or people enrolled in a DLI-registered apprenticeship may do plumbing work, and unlicensed workers must be directly supervised at all times by a licensed journeyworker or master.
The statewide structure you're entering depends on where you live.
As of September 2026, four shapes cover the states that license plumbers individually:
| Statewide structure | States | The license |
|---|---|---|
| Full ladder | 24 jurisdictions — e.g. Texas, Kentucky, Michigan, Wisconsin | Apprentice/trainee → journeyman → master |
| Contractor on top | Connecticut, Idaho, Indiana, Oklahoma, South Dakota | Statewide journeyman license topped by an individual contractor license instead of a 'master' |
| Journeyman only | Alaska, New Mexico, Oregon, Washington | Journeyman-level license; no state master license |
| No journeyman rung | Delaware, Illinois, New Jersey, North Carolina | Master-only, licensed apprentice → licensed plumber, or technician + contractor classes |
What each rung requires — hours, exams, fees — is the subject of our plumbing license requirements guide.
This page is about the line itself: when you can legally work on one side of it without a license of your own.
Two verified carve-outs show how narrow the unlicensed zone is.
Arizona's small-job exemption covers only casual or minor work under $1,000 in aggregate contract price that does not require a local building permit.
In California, the CSLB license requirement reaches any job of $1,000 or more in labor and materials, or any job needing a building permit — a threshold raised from $500 by AB 2622, effective January 1, 2025.
One dollar or one permit changes the answer.
The ladder runs through employment, and plumber jobs are where the registered-apprentice hours start.
States where only cities and counties license plumbers
Seven states have no state plumber license at all: Florida, Kansas, Missouri, Nebraska, Nevada, New York and Wyoming license plumbers through cities and counties, or an industry board.
Ohio is the eighth state with no general state plumber license, but its license lives at the business level — the state licenses plumbing contractors only, and individual plumbers hold no state license.
"No state license" is not "no license required."
It usually means the card you need is issued closer to the job site:
| State | Who issues the license, per our research |
|---|---|
| Florida | Counties and municipalities issue plumbing journeyman licenses under s. 489.1455, Florida Statutes — and they are portable between Florida localities |
| Kansas | Journeyman, master and plumbing contractor licenses are issued locally, under uniform statewide standards (K.S.A. 12-1508 to 12-1511) |
| Missouri | Kansas City issues Journeyman Plumber and Master Plumber certifications, required for individuals performing or supervising plumbing work in the city |
| Nebraska | State law requires anyone installing or repairing sanitary plumbing to hold a master plumber license from the city or village nearest the site, with employees licensed as journeymen by that city or village |
| Nevada | No state journeyman or master license; in Clark County, plumbers must carry an ID card issued through the Nevada Board of Plumbing Examiners (NBOPE) — an industry-founded board working in partnership with the county, not a state agency — and journeyman is the minimum level for working without supervision |
| New York | Plumbing licenses are issued locally; state law (General City Law Article 4, §40-a) provides for examining boards of plumbers in cities |
| Wyoming | Casper licenses Apprentice, Journeyman and Master Plumbers; journeyman and master plumbers need an approved ICC exam (G27-N/G28-N) and a federally recognized apprenticeship or four years in a Casper-licensed shop |
Two more states sit outside the verified lists.
Pennsylvania appears to license the same way — locally, through county programs such as Allegheny County's — and Tennessee appears to have only a limited state credential, with journeyman and master tiers handled locally.
Our research could not confirm either; ask the county or the state office before you rely on the gap.
Where licensing is local, the city is your board
Owning a plumbing company without a license
Owning the company doesn't lift the license requirement — it moves it.
Three patterns cover the states our research verified:
- The master license is the business license. In Georgia, Maine, Kentucky, Delaware, Montana, Wisconsin, Texas, Louisiana, New Jersey, North Dakota, Connecticut and Rhode Island, the individual master (or equivalent) plumber license is what lets a business contract — there is no separate state plumbing-contractor license. The same holds in New York City and under Nebraska's city master licenses. A company in these states contracts through a licensed master — the owner's, or in several states one the business employs.
- The contractor license is the only state license. Ohio licenses plumbing contractors — businesses — and has no individual plumber license. Arizona and California are the same shape: employees are exempt, but the business holds the ROC license — C-37 Plumbing (commercial), R-37 (residential) or CR-37 (dual) — or the CSLB's C-36 Plumbing Contractor classification.
- The qualifier carries it. The license attaches to a person with experience. California's C-36 needs a qualifier with at least four years of journey-level experience in the classification within the 10 years before applying. Arizona's qualifying party needs at least four years of practical or management trade experience, two within the last ten — accredited technical training can count for up to two of the four.
The dollar line matters as much as the org chart.
In California, any job of $1,000 or more in labor and materials — or any job needing a building permit — requires a CSLB license.
A plumbing company that never crosses that line and never pulls a permit is not a plumbing business in any meaningful sense; the unlicensed zone belongs to the handyman, and it is narrow.
The duty also runs uphill: Montana requires that contractors not engage unlicensed persons for licensed work, so the licensed shop is the one checking your registration, not dodging it.
Penalties for unlicensed plumbing
Penalties for working outside the license structure are set state by state, and the amounts our research verified are a handful — enough to show the range, not a national scale:
- Delaware — unlicensed plumbing carries a fine of $1,500–$3,000 for a first offense and $3,000–$6,000 for later offenses.
- Vermont — a specialty plumbing business that hires or employs unlicensed workers for plumbing faces fines up to $1,000 per offense.
- Nevada — a contractor-law penalty rather than a plumber-license one: unlicensed contracting is a misdemeanor on a first offense, with a fine up to $1,000 and up to 6 months in jail, and a category E felony by the third offense.
Notice what the Vermont and Montana rules share with the registration states: the exposure doesn't sit only with the person holding the wrench.
Employing unlicensed workers for plumbing, or engaging them for licensed work, is its own violation — which is why the registration and supervision rules in the first section are conditions, not courtesies.
Career information, not legal advice. Licensing and penalty rules are set by state boards, state contractor-licensing statutes, and city and county offices where licensing is local — and they change. Confirm the current rules with the board or local office where you plan to work before you take any job.