- MI-MP refers to the Michigan Master Plumber License Exam, administered by LARA's Bureau of Construction Codes through PSI Services LLC.
- The exam is 130 questions in 180 minutes with a minimum passing score of 75%.
- Eligibility requires 4,000 hours as a journey plumber over at least the two years before applying, with no lapse in licensure.
- The test includes a drawing-based material takeoff covering back-to-back restrooms, fitting quantities, and drain/vent sizing.
What MI-MP Actually Stands For
MI-MP stands for the Michigan Master Plumber License Exam - the state licensing test that a journey plumber in Michigan must pass to legally hold the title and scope of a master plumber. "MI" is short for Michigan, and "MP" is short for Master Plumber. This is not a national certification, a manufacturer credential, or an association-issued designation. It is a state licensing examination tied directly to Michigan's plumbing code and its statutory framework for skilled trades regulation.
If you've landed here searching for background before you start studying, this page is meant to give you the plain-language answer, then point you toward more detailed resources like the MI-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify guide and the full MI-MP Exam Domains 2026: Complete Guide to All 11 Content Areas breakdown.
Who Issues the Credential
The Michigan Master Plumber License is issued by the Michigan Department of Licensing and Regulatory Affairs (LARA), Bureau of Construction Codes. LARA sets the eligibility rules and approves candidates, while the actual computer-administered exam is delivered by PSI Services LLC, the third-party testing provider. Candidates cannot register for the exam directly with PSI until LARA has reviewed and approved their application.
This two-agency structure matters for planning purposes: your application timeline runs through LARA first, and only after approval does the PSI examination fee and scheduling process begin. For a full walkthrough of dates and deadlines, see MI-MP Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Exam Format and Scoring
The Michigan Master Plumber License Exam is a computer-administered test consisting of 130 questions to be completed within 180 minutes. The minimum passing score is 75%. The PSI examination fee is $100 per attempt, and that fee applies to retakes as well - there is no discounted retake rate.
Testing is available both at PSI test centers and via remote proctoring, with remote master-level testing having become available beginning February 11, 2026. This gives candidates flexibility in scheduling, though both delivery modes follow the same PSI test-center security rules, including a requirement that personal calculators be stored outside the examination room rather than kept at the workstation.
Key Takeaway
Budget for the possibility of a retake at full price - the $100 PSI fee applies every attempt, so passing on your first try has direct cost value. See MI-MP Certification Cost 2026: Complete Pricing Breakdown for the full fee picture.
Open-Book, But Restricted
This exam is open book, but narrowly so. Candidates may bring a bound copy of the 2021 Plumbing Code Book with chapter tabs only. No additional papers, loose notes, or supplementary writing are permitted, and you may not highlight, underline, or index anything inside the reference during the exam itself. The State Construction Code Act (1972 PA 230) and the Skilled Trades Regulation Act (2016 PA 407) are supplied onscreen during the test - you are not allowed to bring personal paper copies of either statute. Effective April 29, 2026, the PSI bulletin confirms the 2021 Plumbing Code Book as the official exam reference.
Because the open-book format is so restrictive, familiarity with the code book's organization - not just its content - becomes a real advantage. Knowing which chapter covers venting methods versus drainage sizing saves precious minutes inside a strict 180-minute window.
Eligibility to Sit for the Exam
To qualify for the Michigan Master Plumber License Exam, a candidate must:
- Be at least 18 years old
- Have accumulated at least 4,000 hours working as a journey plumber
- Have earned those hours over at least the two years immediately preceding application
- Have had no lapse in journey licensure during that two-year period
- Receive LARA approval before registering with PSI
These requirements mean the master exam is not an entry-level test - it's built for working journey plumbers who have already logged substantial field time under an active license. If you're unsure whether your work history qualifies, the detailed breakdown in MI-MP Requirements 2026: Eligibility, Prerequisites & How to Qualify walks through documentation and edge cases.
The 11 Content Domains
PSI's exam content outline for the Michigan Master Plumber License Exam is organized into eleven domains. Understanding what falls under each one is the foundation of any serious prep plan - and it's covered in far more depth in MI-MP Exam Domains 2026: Complete Guide to All 11 Content Areas. Here's the list:
Domain 1: Drainage Systems
Sizing, slope, materials, and layout principles governing how waste and wastewater move out of a building.
- Drain sizing calculations tied to fixture units
Domain 2: General Knowledge
Broad code literacy and foundational plumbing principles that cut across other domains.
- Terminology and code structure familiarity
Domain 3: Fixtures
Fixture requirements, minimum quantities, and installation standards.
- Fixture unit values and clearance rules
Domain 4: Water Distribution
Supply piping sizing, materials, and pressure considerations.
- Pipe sizing methodology
Domain 5: Backflow Protection
Cross-connection control and the devices used to prevent contamination of potable water.
- Device selection based on hazard level
Domain 6: Storm Drains
Sizing and layout of systems managing rainwater and site drainage.
- Storm drainage sizing tables
Domain 7: Special Waste
Handling of waste streams requiring treatment or special disposal methods before entering the sanitary system.
- Interceptor and separator requirements
Domain 8: Testing
Required testing procedures for plumbing systems before approval.
- Pressure and leak test protocols
Domain 9: Inspections
What inspectors check for and at what stages of installation.
- Rough-in versus final inspection points
Domain 10: Venting
Venting methods and sizing to protect trap seals and system integrity.
- Vent sizing tied to drainage fixture units
Domain 11: Knowledge of the Skilled Trades Regulation Act, 2016 PA 407
The statutory framework governing licensure, discipline, and trade regulation in Michigan.
- Licensing authority and enforcement provisions
Notice that venting and drainage each get dedicated domain status - and they also show up together in the practical takeoff question. That overlap is worth building into your study order, a point covered further in MI-MP Cheat Sheet 2026: One-Page Review of Must-Know Facts.
The Material Takeoff Question Style
One of the more distinctive features of this exam is a drawing-based material takeoff component. Rather than only answering discrete multiple-choice questions, candidates work from a plan drawing - commonly involving back-to-back restrooms - and must determine things like:
- Fitting quantities needed for the layout shown
- Correct drain sizing based on the fixtures depicted
- Correct vent sizing and venting method for the configuration
This question style rewards candidates who can read a plan and translate it into code-compliant sizing decisions on the spot, rather than simply recalling isolated facts. It blends Domain 1 (drainage systems), Domain 10 (venting), and Domain 3 (fixtures) into a single applied scenario. Practicing with realistic takeoff-style drawings - not just flashcards - is one of the highest-value things you can do before test day. The MI-MP Study Guide 2026: How to Pass on Your First Attempt walks through how to build takeoff practice into a study schedule.
Key Takeaway
Back-to-back restroom takeoffs test three domains at once - fixtures, drainage, and venting - so treat plan-reading practice as a core study activity, not an afterthought.
After You Pass: Renewal and Scope
Passing the exam and receiving your Master Plumber License isn't the end of the compliance timeline. Licenses must be renewed every three years by April 30, with a $300 renewal fee. In addition, licensees are required to complete code-update training within one year after a new plumbing code is adopted, ensuring master plumbers stay current as code cycles change.
It's also worth restating: the Master Plumber License is a personal trade credential distinct from a plumbing contractor license, which governs the business side of contracting for plumbing work. Holding the master license demonstrates individual technical competency recognized by LARA.
| Item | Detail |
|---|---|
| Exam length | 130 questions / 180 minutes |
| Passing score | 75% minimum |
| PSI exam fee | $100 per attempt (including retakes) |
| Renewal cycle | Every 3 years by April 30 |
| Renewal fee | $300 |
| Reference material | 2021 Plumbing Code Book, bound, chapter tabs only |
Who Hires Master Plumbers in Michigan
Holding a Master Plumber License typically signals to employers that a plumber has met Michigan's highest individual licensing bar for the trade - 4,000 hours of documented journey-level experience plus a passed state exam covering the full scope of plumbing systems design, code, and statute knowledge. This credential often factors into hiring decisions for supervisory field roles, code-compliance oversight, and positions where a company needs a licensed master on staff to pull certain permits or sign off on installations.
If you're evaluating whether pursuing this license makes sense for your career trajectory, including how it may affect job opportunities and long-term positioning in the trade, see MI-MP Jobs and Is the MI-MP Certification Worth It? Complete ROI Analysis 2026.
A Realistic Prep Path
Because the exam mixes code-based recall with an applied material takeoff, an effective prep sequence usually front-loads the domains most tied to calculation - drainage systems, venting, and water distribution - before moving into procedural domains like testing and inspections, and finishing with the Skilled Trades Regulation Act material, which is more about statutory familiarity than calculation.
Core calculation domains
- Drainage systems, venting, water distribution sizing practice
- Get comfortable navigating chapter tabs in your code book quickly
Fixtures, backflow, storm, and special waste
- Practice takeoff-style drawings combining fixtures with drain/vent sizing
- Review backflow device selection scenarios
Testing, inspections, and general knowledge
- Review required test procedures and inspection checkpoints
- Timed practice under the 180-minute limit
Skilled Trades Regulation Act and full review
- Study 2016 PA 407 provisions since it's supplied onscreen, not in your code book
- Full-length timed practice run
For a more detailed weekly plan and self-assessment tools, see the MI-MP Study Guide 2026: How to Pass on Your First Attempt, and check MI-MP Passing Score 2026: Exactly What You Need to Pass to understand exactly what 75% means in terms of missed-question tolerance across 130 questions.
You can also gauge your overall readiness against the exam's difficulty profile in How Hard Is the MI-MP Exam? Complete Difficulty Guide 2026, and review broader performance context in MI-MP Pass Rate 2026: What the Data Shows. Running full practice sessions on our practice test platform before scheduling your real exam is one of the most direct ways to simulate the timed, 130-question format.
Frequently Asked Questions
On mimpexam.com, MI-MP always refers to the Michigan Master Plumber License Exam administered by LARA's Bureau of Construction Codes through PSI Services LLC. Other industries may use the same initials for unrelated credentials, but this site covers only the Michigan plumbing license exam.
LARA's Bureau of Construction Codes sets eligibility and approves applications, while PSI Services LLC delivers the computer-administered exam at test centers or via remote proctoring.
Only a bound copy of the 2021 Plumbing Code Book with chapter tabs. No loose papers, added notes, highlighting, underlining, or indexing are allowed. The State Construction Code Act and the Skilled Trades Regulation Act are provided onscreen during the test.
The bulletin does not cap attempts in the facts provided here, but note that the $100 PSI fee applies to every attempt, including retakes, so there's a real cost incentive to prepare thoroughly the first time.
No. The Master Plumber License certifies an individual's trade competency, while the plumbing contractor license governs the ability to contract for plumbing work as a business. They are separate credentials with separate requirements.