- MD-MP is the Maryland Master Plumber/Gas Fitter exam: 100 scored questions, 240 minutes, 70% to pass.
- Gas Appliances and Piping is the largest domain, worth 40 of 100 questions.
- Eligibility requires two years as a journey licensee plus 3,750 supervised hours under a master.
- Applications have been online-only through PSI since March 31, 2025; retesting is capped at once every 30 days.
What Is MD-MP?
MD-MP stands for the Maryland Master Plumber License Exam, the state's credentialing test administered through the Maryland State Board of Plumbing under the Maryland Department of Labor. The version most licensees actually sit for is the combined Master Plumber/Gas Fitter examination, which folds gas-related competencies directly into the same test rather than requiring a separate gas-fitting exam. If you're researching this credential for the first time, this overview pairs well with our broader MD-MP Certification explainer and the detailed MD-MP Requirements 2026 breakdown.
Passing MD-MP is the gate between holding a Maryland journey plumber license and becoming eligible to apply for a master license - the credential that lets you pull permits, supervise crews, and legally contract plumbing work in your own name across most of the state.
Who Administers the MD-MP Exam
Two organizations share responsibility for MD-MP. The Maryland State Board of Plumbing, housed within the Maryland Department of Labor, sets eligibility rules, approves reference materials, and issues the resulting master license. PSI Examination Services delivers the actual test - booking appointments, administering the computer-based questions, and reporting scores back to the board.
This split matters practically: policy questions (eligibility, renewal, insurance) go to the Board of Plumbing, while scheduling, application submission, and day-of-test logistics run through PSI. Since March 31, 2025, examination applications have been online-only, so there's no paper submission path anymore.
Exam Format and Structure
MD-MP is a computer-based, multiple-choice exam consisting of 100 scored questions to be completed in 240 minutes. You need a raw score of 70% to pass. PSI may seed the exam with five to 10 additional unscored experimental questions used to evaluate future test content - the time spent on those questions doesn't count against your four-hour allowance, so the clock effectively protects you from being penalized for them.
The exam is open book, but the rules around what "open book" means are specific:
- Permanent tabs, highlighting, and underlining in your approved reference books are allowed.
- Handwritten notes, loose additional papers, and third-party study guides are prohibited inside the testing room.
- A board-linked bulletin dated September 1, 2024 lists the 2018 IPC and 2018 IFGC among approved candidate-supplied references.
Key Takeaway
Before buying code books, check the current PSI candidate bulletin - June 2026 board minutes discuss 2024-code revisions, and you want to confirm which edition your specific booked exam actually references before you invest in study materials.
For a deeper dive into exactly what passing looks like numerically, see MD-MP Passing Score 2026: Exactly What You Need to Pass.
The 10 MD-MP Exam Domains
MD-MP is built from 10 content domains, each with its own share of the 100 scored questions. Knowing the weighting changes how you should allocate study time - a domain worth 40 questions deserves far more attention than one worth three.
| Domain | Questions |
|---|---|
| 1. Plumbing Fundamentals and Safety | 5 |
| 2. Materials, Uses, and Specifications | 6 |
| 3. Traps, Interceptors, and Backwater Valves | 4 |
| 4. Plumbing Fixtures, Fixture Fittings, and Plumbing Appliances | 4 |
| 5. Water Supply Systems | 8 |
| 6. Backflow Prevention | 10 |
| 7. Drain, Waste, and Vent Systems | 13 |
| 8. Special Topics | 3 |
| 9. Gas Appliances and Piping | 40 |
| 10. Plumbing Mathematics | 7 |
Domain 9: Gas Appliances and Piping
This is the single largest domain by a wide margin - 40 of 100 questions, meaning a candidate can't pass MD-MP without genuine gas-fitting competence. It reflects the exam's combined Master Plumber/Gas Fitter scope.
- Gas appliance venting, sizing, and installation clearances
- Piping material selection and sizing calculations for gas systems
- Code-based requirements pulled from the IFGC reference
Domain 7: Drain, Waste, and Vent Systems
The second-heaviest domain at 13 questions. DWV topics test your understanding of proper slope, venting configurations, and waste system sizing under the IPC.
- Vent sizing and configuration rules
- Drainage fixture unit calculations
- Trap arm and cleanout placement requirements
Domain 6: Backflow Prevention
Worth 10 questions, this domain overlaps directly with the separate 32-hour backflow prevention device testing certificate you must already hold to sit for the exam.
- Device types and appropriate application by hazard level
- Testing and installation requirements
- Cross-connection control principles
For a full walkthrough of every content area - including the lighter-weighted domains that still need coverage - read MD-MP Exam Domains 2026: Complete Guide to All 10 Content Areas. If you're trying to gauge overall difficulty before committing study hours, How Hard Is the MD-MP Exam? Complete Difficulty Guide 2026 puts the domain weighting into context.
Eligibility Requirements
MD-MP isn't open to anyone off the street. Standard eligibility requires:
- A journey plumber license held for at least two years
- 3,750 supervised training hours worked under a licensed master plumber
- A current, approved 32-hour backflow prevention device testing certificate
- Work records and identification submitted through PSI's application process
These aren't optional documentation checkboxes - PSI verifies them before issuing an authorization to test. If any piece is missing or expired (particularly the backflow certificate), your application will stall. Full detail on how each requirement is verified lives in MD-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Registration, Fees, and Scheduling
The exam itself costs $65 per attempt. That fee is separate from licensing costs: under the fee schedule effective July 1, 2025, both the initial master license and each renewal run $87.50. Applications are submitted entirely online - there is no paper option as of March 31, 2025.
If you don't pass on a given attempt, you can retest, but not more often than every 30 days. That cooling-off period is a hard rule, not a suggestion, so plan your study calendar with that gap in mind rather than assuming you can rebook immediately. A complete cost breakdown, including how the exam fee stacks against licensing fees over a license cycle, is available in MD-MP Certification Cost 2026: Complete Pricing Breakdown. For scheduling windows and deadlines specifically, see MD-MP Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Licensing After You Pass
Passing the exam doesn't automatically hand you a license. You must apply for your master license within one year of passing, or the passing result can lapse. Once issued, a master license runs for two years from issuance, and general plumbing-license renewal carries no continuing education requirement - a notable difference from many other trade licenses.
If you plan to contract independently rather than work for someone else's license, you'll also need insured-to-contract status: at least $300,000 in general liability coverage and $100,000 in property-damage coverage per occurrence. That's a business decision separate from the exam itself, but it's worth planning for before you pass, not after.
One more wrinkle worth flagging early: Baltimore County and the WSSC (Washington Suburban Sanitary Commission) service area maintain their own separate licensing authorities. Passing MD-MP and holding a state master license doesn't automatically cover work in those jurisdictions - check local requirements if you plan to work there.
Who Uses the MD-MP Credential
A Maryland master plumber license (earned by passing MD-MP) is the credential that lets a plumber pull permits, run a licensed plumbing business, or serve as the qualifying master for a company. It's used by:
- Independent contractors starting their own plumbing business
- Mechanical and plumbing contracting firms that need a licensed master of record
- Journey plumbers seeking supervisory roles on commercial or residential crews
- Gas-fitting specialists, given the exam's heavy Gas Appliances and Piping weighting
If you're weighing whether pursuing the license is worth the time and testing fees against your career goals, Is the MD-MP Certification Worth It? Complete ROI Analysis 2026 and MD-MP Salary Guide 2026: Complete Earnings Analysis dig into that decision. For open-role research once you're licensed, see MD-MP Jobs.
How to Prepare Efficiently
Because Gas Appliances and Piping alone accounts for 40% of scored questions, an efficient study plan front-loads that domain rather than treating all 10 domains equally. Drain, Waste, and Vent Systems (13 questions) and Backflow Prevention (10 questions) come next in priority; the remaining domains - each worth three to eight questions - can be batched into shorter review blocks.
Gas Appliances and Piping
- Work through IFGC sizing and venting rules until they're second nature
- Practice gas pipe sizing calculations by hand
DWV and Backflow Prevention
- Drill drainage fixture unit tables and vent sizing
- Cross-reference backflow device types with your 32-hour certificate material
Remaining domains and full-length practice
- Cover Materials, Water Supply, Fixtures, Traps, Math, Fundamentals, and Special Topics
- Run timed practice sets to build comfort with the 240-minute pace
Because the exam is open book, practice using your actual approved references - tabbing and highlighting the 2018 IPC and 2018 IFGC ahead of time is part of your prep, not an afterthought. For a condensed review before test day, our MD-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts summarizes the highest-yield facts. A more complete week-by-week plan is in MD-MP Study Guide 2026: How to Pass on Your First Attempt, and you can build timed familiarity with the question style on our practice test platform before booking your PSI appointment.
Frequently Asked Questions
MD-MP refers to the Maryland Master Plumber License Exam, administered by the Maryland State Board of Plumbing through PSI Examination Services. See MD-MP Meaning and What Does MD-MP Stand For? for more detail.
The exam has 100 scored multiple-choice questions with a 240-minute time limit and a 70% passing score. PSI may add up to 10 unscored experimental questions, but their response time doesn't count against your four hours.
No. The exam is open book for approved references like the 2018 IPC and 2018 IFGC, with permanent tabs, highlighting, and underlining allowed. Handwritten notes, loose papers, and outside study guides are prohibited.
Retesting is allowed no more often than every 30 days, so budget your restudy time and the $65 retest fee accordingly.
No. General plumbing-license renewal in Maryland carries no CE requirement, though the license itself runs on a two-year cycle from issuance with an $87.50 renewal fee.