Maryland licenses plumbers in three tiers, apprentice, journeyman, and master, with a 70 percent passing score on the PSI exam and roughly 11,250 supervised hours to reach master. Here is the full ladder, the real fee tables, and what a plumbing business needs to legally operate.
Maryland licenses plumbers at the state level through the Maryland Board of Plumbing, one of the licensing boards inside the Maryland Department of Labor's Division of Occupational and Professional Licensing. If you want to work on plumbing or gas systems anywhere in Maryland, you need a license from this board, and if you want to run a plumbing business, the ladder ends at the Master Plumber/Gas Fitter license, because in Maryland only a master can contract plumbing work and pull permits under their own license number.
At a glance
- Who issues it: the Maryland Board of Plumbing, inside the Maryland Department of Labor
- Who can contract: only a master can contract plumbing work and pull permits under their own license number
- Hours: roughly six years and 11,250 supervised hours from apprentice to master
- Exam: PSI, 100 questions in 240 minutes (4 hours), 70 percent to pass, $65 exam fee
- Board fees: $18.50 for apprentice, $43.50 for journeyman, and $87.50 for master
This guide walks the full ladder: apprentice, journeyman, and master, plus the separate natural gas fitter track, what the board and PSI actually charge, and what happens at the top of the ladder when a business needs a master's license to operate.
New to licensing in Maryland? Start with the Maryland contractor license requirements.
Maryland's Plumbing License Ladder at a Glance
Maryland uses a classic three tier structure, and every tier is a combined Plumber/Gas Fitter license. The plumbing license in Maryland includes gas fitting authority, which is not true in every state.
| License | Prerequisite | Hours required | Backflow training |
|---|---|---|---|
| Apprentice Plumber/Gas Fitter | Age 16 or older | None | No |
| Journeyman Plumber/Gas Fitter | Apprentice license held 4+ years | 7,500 hours under a master | 32 hours, board approved course |
| Master Plumber/Gas Fitter | Journey license held 2+ years | 3,750 additional hours under a master | Current 32 hour certificate required |
| License | Exam | Passing score |
|---|---|---|
| Apprentice Plumber/Gas Fitter | None | N/A |
| Journeyman Plumber/Gas Fitter | PSI comprehensive written exam | 70 percent |
| Master Plumber/Gas Fitter | PSI comprehensive written exam | 70 percent |
Every hour on the ladder is earned under the direction and control of a licensed master plumber. You cannot accumulate qualifying hours working unsupervised or under an unlicensed boss. The master you work for is the anchor of your entire path.
Step 1: Apprentice Plumber/Gas Fitter
The entry point is simple: you must be at least 16 years old. There is no exam at the apprentice level. The board's current fee schedule lists an $18.50 fee for the apprentice license, and the board says an original license arrives by mail within about two weeks of applying.
Apprentices work under the direction and control of a licensed master plumber while they build hours. Maryland's four year apprenticeship window matches the 7,500 hour requirement for the journeyman exam.
One rule catches people off guard: by law, an apprentice plumber/gas fitter license may only be renewed for two consecutive cycles before you must take the journey exam. Maryland does not let you park at the apprentice level forever, the ladder is designed to move you up.
Step 2: Journeyman Plumber/Gas Fitter
To qualify for the journeyman license you must have:
- Held your apprentice license for at least four years
- Completed 7,500 hours of training under the control and direction of a licensed master plumber
- Completed 32 hours of training in backflow prevention device testing through a board approved course
- Passed the comprehensive written examination with a score of at least 70 percent
The backflow requirement is distinctive: Maryland writes 32 hours of backflow prevention training into the journeyman path itself. Budget for it early, because you cannot sit the exam without it.
Maryland statute lets the board waive qualifications for plumbers who already hold a current journey license from Baltimore County or the Washington Suburban Sanitary Commission (WSSC), and the board issues reciprocal journey and master licenses to them. The board requires you to hold both the plumbing and the gas portion of that local license. That reciprocal path is worth checking before you assume you have to start over.
The exam
PSI Examination Services provides all testing for the Maryland State Board of Plumbing. You register directly with PSI, upload proof of your hours worked, your backflow certification, and a copy of your driver's license, and schedule at a PSI testing center; the board and the PSI bulletin list sites that include Baltimore, College Park, Hagerstown, and Salisbury. According to PSI's Candidate Information Bulletin for the board, the journey and master plumber/gas fitter exams are each 100 questions in 240 minutes (4 hours) with a minimum passing score of 70 percent, and the exam fee, paid directly to PSI, is $65. Review the bulletin before registering, since it carries the current content outline and fee.
Step 3: Master Plumber/Gas Fitter
The master license is the business license of Maryland plumbing. To qualify you must have:
- Held a journey license for at least two years
- Completed 3,750 hours of additional training under the direction and control of a licensed master plumber
- Completed 32 hours of backflow prevention device testing training, with a current certificate
- Passed the comprehensive written master examination through PSI with a score of at least 70 percent
- Submitted proof of liability insurance of at least $300,000 for bodily injury and $100,000 for property damage (Md. Business Occupations and Professions §12-501), which a master must carry to contract plumbing work
Add it up and the full path from first day as an apprentice to master runs roughly six years and 11,250 supervised hours: four years and 7,500 hours to journeyman, then two more years and 3,750 hours to master.
Reciprocity runs a little wider at the master level. The board states that it reciprocates only with Delaware, WSSC, and Baltimore County, and that the Delaware agreement covers the Master Plumber/Gas Fitter license only. The board's original master license fee is $87.50.
What Each License Costs
The Maryland Board of Plumbing's Forms and Fees page (updated July 1, 2025) and PSI's candidate bulletin list these amounts:
| License | Original license fee (board) | Renewal fee, every 2 years (board) | PSI exam fee |
|---|---|---|---|
| Apprentice Plumber/Gas Fitter | $18.50 | $18.50 | No exam |
| Journeyman Plumber/Gas Fitter | $43.50 | $43.50 | $65 |
| Master Plumber/Gas Fitter | $87.50 | $87.50 | $65 |
| Journeyman Natural Gas Fitter | $68.50 | $31.50 | $25 |
| Master Natural Gas Fitter | $150.50 | $43.50 | $65 |
The exam fee is paid directly to PSI, not to the board. Fees change, so verify the exact current amounts with the Maryland Department of Labor and PSI before you apply.
By national standards these are modest fees. Maryland's barrier to entry is not money, it is the 11,250 supervised hours.
The Natural Gas Fitter Track
Maryland also runs a parallel natural gas fitter ladder (apprentice, journeyman, master) for gas only work. A few details worth knowing:
- A journeyman natural gas fitter needs 3,750 working hours as an apprentice over at least two years under a licensed master gas fitter or master plumber, plus an approved training course and an exam.
- Anyone who already holds a current journey or master gas fitter license from Baltimore County or WSSC can obtain the like state natural gas fitter license, skipping the apprenticeship route entirely. The board names those two local programs in its qualification rules.
- There is also a propane gas fitter certification; one way to qualify is a current certificate of completion of the National Propane Gas Association's Distribution Systems Operations training program.
Watch the Local Layer: WSSC and County Rules
Maryland's state license is the foundation, but plumbing in the Washington suburbs has a second, separate layer. The Washington Suburban Sanitary Commission (WSSC) issues its own plumber and gas fitter licenses for work in Montgomery and Prince George's counties, and WSSC Water says a WSSC licensed plumber or gas fitter performs most major plumbing projects there. Baltimore County runs its own plumbing board as well, and the state board warns that anyone working in Baltimore County, Prince George's County, or Montgomery County may be required to pass an additional local examination.
Local jurisdictions also administer their own permits and inspections. If you plan to work in the D.C. suburbs or in Baltimore County, check that agency's licensing requirements alongside your state license. The state's own reciprocity rules reference WSSC and Baltimore County licenses by name, which tells you how real this second layer is.
What Happens If You Work Unlicensed
Maryland does not treat unlicensed plumbing work as a paperwork issue. Under Md. Business Occupations and Professions §12-607, practicing without a license is a misdemeanor carrying a fine of up to $100, up to six months in jail, or both, for each day the violation continues, and the board can add a penalty of up to $5,000 for each violation. That exposure is one more reason a plumbing business needs a genuine, currently licensed master plumber attached to it before it takes on work, not after.
The Part Most Guides Skip: Who Holds the License When You Build a Business?
Here is the structural fact that matters once you move from working as a plumber to running a plumbing company: the master license is personal, but the business depends on it. Maryland's plumbing statute limits a journey plumber's license to work performed under a master's direction and control, and the state's plumbing regulations require that all plumbing work be performed, or supervised and approved, by a licensed master plumber who is familiar with its design and purpose and available to direct and control the journey and apprentice plumbers on the job. Permits pull against a master's license number. A plumbing company without a master plumber attached to it cannot lawfully contract plumbing work, no matter how many journeymen it employs.
Maryland does not use a separate title like "RME" or "qualifying individual" for plumbing the way some general contracting boards do. The master plumber IS the qualifier.
That creates the classic qualifier problem:
- An investor or general contractor wants to launch or expand a plumbing operation in Maryland but nobody in the company holds a Maryland master plumber license.
- An established company loses its master, retirement, resignation, illness, and its ability to contract new work is suddenly at risk.
- An out of state plumbing company enters Maryland and discovers its home state master's license means nothing to the Maryland board.
The solution is the same in each case: the company brings on a Maryland licensed master plumber to hold the license for the business. Done right, that person is a full time W-2 employee with genuine involvement in the company's plumbing operations, supervising work, signing off on permits, and carrying the compliance responsibility the license implies.
This is exactly what a qualifying agent is, and it is the model we place under. Real employment. Real supervision. A person who qualifies the business, not a name borrowed on paper.
If your company needs a Maryland master plumber to operate, or you hold a master license and want to understand what it is worth to a company that needs one, start with what a qualifying agent is, then look at hiring a qualifying agent or becoming one. Every situation is different, so we scope each engagement through a consultation. You can also learn how licensing works for the trade next door in our contractor license overview.
FAQ
How long does it take to become a master plumber in Maryland?
Roughly six years minimum: four years and 7,500 hours as an apprentice to reach journeyman, then two years and 3,750 more hours to qualify for the master exam. The statute lets up to 1,500 hours of approved school study count toward the 7,500 hour journeyman requirement; beyond that, there is no experience shortcut.
How much does a Maryland plumbing license cost?
The board's fee schedule, updated July 1, 2025, lists original license fees of $18.50 for apprentice, $43.50 for journeyman, and $87.50 for master, and PSI charges a $65 exam fee for the journey and master exams. Fees are set by the board and testing vendor and change, so verify current amounts before applying. The real investment is the supervised hours. If you are asking what it costs a company to secure a master plumber to qualify its business, that depends on your situation, request a consultation and we will walk you through the drivers.
What score do I need to pass the Maryland plumbing exam?
70 percent. Maryland regulation COMAR 09.20.02.11 sets a passing score of 70 for every license the board issues, and PSI's candidate bulletin lists a 70 percent minimum on the 100 question journey and master plumber/gas fitter exams.
Does Maryland have a statewide plumbing license?
Yes. Unlike states such as Pennsylvania where plumbing licensing is local, Maryland licenses plumbers at the state level through the Board of Plumbing. Watch for the extra WSSC and Baltimore County layer described above.
Can my company do plumbing work with only journeymen on staff?
No. Journeymen and apprentices work under a master. To contract plumbing work and pull permits, the business needs a licensed Maryland master plumber, which is why companies without one hire a qualifying agent as a W-2 employee.
Do I need a separate gas license?
The standard Maryland ladder is a combined Plumber/Gas Fitter license, so plumbing licensees carry gas fitting authority at their tier. The separate natural gas fitter and propane certifications exist for gas only specialists.
Sources
- Maryland Board of Plumbing, License Requirements; Forms and Fees; Taking the Exam; Licensing FAQs, retrieved 2026-09-23
- PSI Candidate Information Bulletin, Maryland State Board of Plumbing, retrieved 2026-09-23
- Maryland Code, Business Occupations and Professions §§12-302, 12-305, 12-307, 12-501, 12-607, retrieved 2026-09-23
- COMAR 09.20 (Board of Plumbing), including 09.20.02.01 and 09.20.02.11, retrieved 2026-09-23
- Maryland OneStop, Journeyman Plumber/Gas Fitter License, retrieved 2026-09-23
- Maryland OneStop, Master Plumber/Gas Fitter License, retrieved 2026-09-23
- Maryland OneStop, Journeyman Natural Gas Fitter License, retrieved 2026-09-23
- WSSC Water, Plumbing & Fuel Gas Inspections, retrieved 2026-09-23.
Requirements and fees summarized from the Maryland Board of Plumbing, Maryland statute and regulation, and PSI's candidate bulletin as of 2026-09-23. Fees, exam scores, and requirements are set by the board and testing vendor and change, always verify current figures with the Maryland Department of Labor and PSI before applying.
If your plumbing company needs a Maryland licensed master plumber to operate, or you want to talk through how qualifying works before you commit to a hire, call 615-219-2110 or start with HireAQualifyingAgent.
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Disclaimer: This article is provided for educational and informational purposes only. It does not constitute legal advice, licensing guidance, or an offer of services. Licensing requirements vary by jurisdiction. For specific compliance questions, contact The Licensing Company for a confidential consultation.