- What Is MD-MP Certification?
- Who Administers the MD-MP Exam?
- Exam Format and Structure
- The 10 MD-MP Exam Domains
- Eligibility Requirements
- Fees, Registration, and Application Rules
- How to Prepare for the MD-MP Exam
- After You Pass: Licensing and Renewal
- Who Hires MD-MP License Holders?
- Frequently Asked Questions
- MD-MP is the Maryland Master Plumber/Gas Fitter exam, administered through PSI Examination Services for the Maryland State Board of Plumbing.
- The exam has 100 scored multiple-choice questions in 240 minutes, plus up to 10 unscored experimental items; passing requires 70%.
- Gas Appliances and Piping is the heaviest domain at 40 of 100 questions - nearly half the exam.
- Candidates need a journey license held two years or longer plus 3,750 supervised hours under a licensed master before applying.
What Is MD-MP Certification?
MD-MP refers to the Maryland Master Plumber License Exam - the combined Master Plumber/Gas Fitter examination administered under the authority of the Maryland State Board of Plumbing, part of the Maryland Department of Labor. Passing this exam is the credentialing step that allows a licensed journeyman to move up to master plumber status in Maryland, which in turn opens the door to pulling permits, supervising crews, and running a licensed plumbing business or division.
Unlike a generic trade certificate, MD-MP is a state-issued license tied directly to Maryland code enforcement. It is not a national voluntary credential - it is the legal gateway to working as a master plumber and gas fitter inside the state. If you are still deciding whether this is the right path for your career, the overview at What Is MD-MP? and the plain-language breakdown in MD-MP Meaning are good companion reads alongside this article.
Who Administers the MD-MP Exam?
Two organizations sit behind the MD-MP process:
- Maryland State Board of Plumbing / Maryland Department of Labor - sets eligibility rules, approves candidate references, issues the license, and manages renewals.
- PSI Examination Services - delivers the computer-based test, verifies candidate documentation (including work records, identification, and backflow certification), and reports results.
It's worth noting that Baltimore County and the WSSC (Washington Suburban Sanitary Commission) service area maintain their own separate licensing authorities. Passing the state MD-MP exam does not automatically grant working privileges in those jurisdictions - plumbers working across county lines should confirm local requirements independently.
Exam Format and Structure
The MD-MP exam is a computer-based, multiple-choice test. Here's exactly what candidates sit down to on test day:
- 100 scored questions answered within a 240-minute (four-hour) window.
- Passing score: 70%. For the specific math behind that threshold, see MD-MP Passing Score 2026: Exactly What You Need to Pass.
- PSI may insert five to 10 unscored experimental questions mixed into the test. These don't count toward your score, and the time spent on them is excluded from the four-hour allowance - so the clock effectively pauses for that portion.
- The exam is open book. You may bring approved reference material with permanent tabs, highlighting, and underlining. Handwritten notes, loose additional papers, and outside study guides are explicitly prohibited during testing.
Key Takeaway
Because experimental questions are unmarked and mixed in, treat every question on screen as if it counts - pacing yourself against 100 questions over four hours, not fewer.
The 10 MD-MP Exam Domains
MD-MP content is organized into 10 domains with fixed question counts totaling 100. Understanding this weighting is the single most important strategic input for your study plan - a full breakdown lives in MD-MP Exam Domains 2026: Complete Guide to All 10 Content Areas, but here's the distribution:
| 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
Because this domain alone carries nearly 40% of the exam, candidates need deep, working familiarity with gas piping sizing, appliance venting, and connection requirements as covered in the approved code references.
- Allocate more study hours here than to any other single domain
- Cross-reference practice questions against your approved code book, not memory alone
- Revisit this domain in your final review pass before test day
Domain 7: Drain, Waste, and Vent Systems
At 13 questions, DWV systems form the second-largest content block. Expect questions on trap arrangements, venting configurations, and drainage sizing that build on fundamentals from Domain 3.
- Pair this domain with Domain 3 (Traps, Interceptors, and Backwater Valves) during review since the topics overlap
- Practice reading system diagrams quickly - layout questions are common in this domain
Domain 6: Backflow Prevention
With 10 questions, backflow prevention is directly tied to a hard eligibility requirement: candidates must hold a current, approved 32-hour backflow prevention device testing certificate just to sit the exam. Knowing the devices, testing procedures, and installation contexts cold pays off twice - once on the certificate, once on the test.
- Review device types and their approved applications
- Understand where backflow prevention intersects with the water supply domain
The remaining domains - Plumbing Fundamentals and Safety, Materials, Fixtures and Fittings, Water Supply Systems, Special Topics, and Plumbing Mathematics - carry smaller but still scored allocations. None can be skipped entirely, since a handful of missed questions across several smaller domains adds up quickly against a 70% passing bar.
Eligibility Requirements
Maryland sets a clear, experience-based path to sit the MD-MP exam:
- Journey 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.
- Supporting work records and identification submitted to PSI as part of the application review.
These prerequisites exist to confirm hands-on field experience before a candidate takes on master-level supervisory and permitting responsibility. If you're mapping out your timeline toward eligibility, MD-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify goes deeper into how these hours and documentation are typically verified.
Fees, Registration, and Application Rules
A few mechanical details matter here, since they directly affect your budget and timeline:
- Exam fee: $65 per attempt.
- Initial master license and each renewal: $87.50, under the fee schedule effective July 1, 2025.
- Applications are online-only as of March 31, 2025 - there is no paper submission pathway.
- Retesting is allowed no more often than every 30 days if you don't pass on the first attempt.
- Once you pass, you must apply for the license within one year of your passing date, or you risk having to retest.
For the full cost picture across exam attempts, licensing, and insurance, see MD-MP Certification Cost 2026: Complete Pricing Breakdown. And if you're trying to plan around retest windows and application deadlines, MD-MP Exam Dates 2026: Testing Windows, Deadlines & Scheduling walks through the scheduling logistics in more detail.
How to Prepare for the MD-MP Exam
Because the exam is open book with permanent tabs and highlighting allowed, preparation isn't just about memorization - it's about knowing your approved references well enough to locate the right code section quickly under time pressure. A few MD-MP-specific priorities:
- Tab your approved 2018 IPC and IFGC copies (or the current approved edition) by domain, weighting your tab density toward Gas Appliances and Piping given its 40-question share.
- Since handwritten notes and outside study guides are barred from the testing room, build your reference navigation skill now - tabs and highlighting are your only in-exam aids.
- Practice full-length timed sets that mirror the 100-question, four-hour format so you develop a realistic sense of pacing across all 10 domains.
Foundations and Smaller Domains
- Plumbing Fundamentals and Safety, Materials, Traps and Interceptors, Fixtures and Fittings
- Build and tab your approved code references
Water Supply, Backflow, and DWV
- Deep review of Water Supply Systems and Backflow Prevention
- Drain, Waste, and Vent Systems practice questions
Gas Appliances and Piping (Heaviest Domain)
- Dedicate the largest block of study time here given its 40-question weight
- Work timed practice sets isolating gas sizing and venting questions
Full Simulation and Math Review
- Plumbing Mathematics and Special Topics review
- One full 100-question, 240-minute practice run
For a more complete week-by-week strategy, read MD-MP Study Guide 2026: How to Pass on Your First Attempt. If you want an honest read on how tough this exam really is before committing your study hours, How Hard Is the MD-MP Exam? Complete Difficulty Guide 2026 covers that directly, and a condensed reference is available in MD-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts. You can also run realistic practice questions on our practice test platform to get comfortable with the format before test day.
After You Pass: Licensing and Renewal
Passing the exam is not the finish line - it's the start of a one-year clock. Candidates must apply for the actual license within one year of their passing date. Once issued, the master plumber license runs for two years from issuance, and general renewal carries no continuing education requirement.
If your business intends to contract directly using the master license, Maryland's insured-to-contract status requires at least $300,000 in general liability coverage and $100,000 in property-damage coverage per occurrence. This is a separate business requirement from the personal licensing steps and is worth planning for well before you're ready to bid jobs independently.
Key Takeaway
Mark your calendar the day you pass - the one-year application window and the two-year license term both start ticking from fixed dates, not from when it's convenient to file paperwork.
Who Hires MD-MP License Holders?
A Maryland master plumber license is typically sought by plumbing contracting firms, mechanical contractors, property management companies, and municipal or institutional facilities departments that need someone qualified to pull permits, supervise journeymen, and sign off on gas and plumbing installations. Because the exam combines master plumber and gas fitter content, license holders are positioned for roles spanning both standard plumbing work and gas piping/appliance projects - a combination that many single-scope credentials don't offer.
If you're weighing whether the investment of exam fees, licensing costs, and study time pays off in your specific market, Is the MD-MP Certification Worth It? Complete ROI Analysis 2026 and MD-MP Salary Guide 2026: Complete Earnings Analysis dig into that question further. For active openings and how employers typically list this license in job postings, see MD-MP Jobs. Structured pathways into the required supervised hours are covered in MD-MP Training.
Curious how recent candidates have actually performed? The board reported eight passes among 20 Master Plumber/Gas Fitter candidates in May 2026 - a single-month figure, not a first-attempt or overall pass rate. For the full context on what that number does and doesn't tell you, see MD-MP Pass Rate 2026: What the Data Shows.
Frequently Asked Questions
MD-MP refers to the Maryland Master Plumber License Exam, specifically the combined Master Plumber/Gas Fitter examination administered by PSI Examination Services for the Maryland State Board of Plumbing. See What Does MD-MP Stand For? for more detail.
The exam includes 100 scored multiple-choice questions to be completed within 240 minutes, with a passing score of 70%. PSI may add five to 10 unscored experimental questions, and time spent on those is excluded from the four-hour limit.
Gas Appliances and Piping, which carries 40 of the 100 scored questions - by far the largest domain on the exam. Drain, Waste, and Vent Systems (13 questions) and Backflow Prevention (10 questions) are the next-largest priorities.
No. The exam is open book, and you may use approved references with permanent tabs, highlighting, and underlining, but handwritten notes, additional loose papers, and outside study guides are prohibited.
Retesting is allowed no more often than every 30 days. Once you do pass, you must apply for your license within one year of your passing date.