How to Start a Plumbing Business in Maryland: Master Plumber and Gas Fitter License

You cannot start a plumbing business in Maryland on paperwork alone. The license is personal, the experience hours are personal, and the business entity you form afterward has to be built around the license holder. Get the sequence right and the process is straightforward. Get it wrong and you can end up with an LLC that cannot bid the work you planned to do. This guide covers the license path from apprentice to master plumber and gas fitter, the fees the State Board of Plumbing lists, and the business filings that come after.

Maryland plumbing licenses are issued at the state level for most of the state. Two areas are exceptions: Baltimore County, and the Washington Suburban Sanitary Commission (WSSC) area covering Montgomery and Prince George's counties. Those authorities issue their own licenses and have their own plumbing code. Before you spend money on anything, confirm which authority covers the jobs you plan to take.

Maryland plumbing license classes and fees

The State Board of Plumbing updated its fee schedule effective July 1, 2025. These are the figures the Board lists. Confirm them on the Board's page before you file, because fee schedules change.

License class	Original fee	Renewal fee	Experience required
Apprentice plumber or gas fitter	$18.50	$18.50	Starting license
Journey plumber or gas fitter	$43.50	$43.50	4 years as an apprentice and 7,500 hours
Master plumber or gas fitter	$87.50	$87.50	Two years as a journey plumber, then 3,750 hours under a master
Master natural gas fitter	$150.50	Confirm with the Board	Confirm with the Board

The schedule summarized here does not list a renewal fee for the master natural gas fitter class, so confirm that number before you budget for renewal. Plumbing and gas fitting are separate tracks. If your business will install or repair gas lines, plan for the gas class from the start rather than assuming your plumbing license covers that work.

What you need before you start

• A dated work log for every hour you claim, with job address, task type, supervising master's name, and license number
• Signed verification from each supervising master, collected as you go, not reconstructed at the end
• Identification and any forms the Board requires for your application (confirm the current list with the Board)
• A payment method for the application fee and any exam fee
• Two or three name options for your business, each checked in the SDAT entity search at https://egov.maryland.gov/businessexpress/entitysearch
• A Maryland street address for your business and a resident agent who meets Maryland's requirements
• A Maryland Business Express account at https://egov.maryland.gov/businessexpress for online filings
• A list of the counties where you will work, so you can check local permit and registration rules early

Step-by-step: from apprentice to licensed business owner

1. Confirm your licensing authority. Check the Maryland Department of Labor's plumbing licensing pages at labor.maryland.gov. If your work is in Baltimore County or the WSSC area, contact that authority directly. Maryland Labor also lists local plumbing boards or offices for Anne Arundel, Baltimore County and WSSC, so confirm local permit and registration rules with each county where you plan to work. Ask for written confirmation of the license you need for the work you intend to sell.
2. Choose your target class and work backward from the hours. A journey license requires 4 years as an apprentice and 7,500 hours. A master license requires two years as a journey plumber and then 3,750 hours under a master. Add those numbers to your calendar before you commit to a timeline. If you plan to run a company as the master, you are looking at years of documented work, not months.
3. Register as an apprentice and log hours from day one. Treat the work log as a legal record. Record the date, the job address, the hours worked, the task, and the supervising master. Have your supervisor sign the log on a regular schedule. Hours that cannot be documented are the most common reason an experience file stalls, so ask the Board what documentation format it accepts before you start logging.
4. Advance to journey, then master. When your hours meet the requirement for the next class, file the application and pay the original fee: $43.50 for journey, $87.50 for master, or $150.50 for master natural gas fitter. Renewals for the plumbing and gas fitting classes are listed at the same amounts as the original fee, with the natural gas renewal to be confirmed.
5. Plan for the examination. Confirm with the Board whether the class you are applying for requires an exam, the exam fee, how to register, which study references the Board lists, and where the test is offered. This guide does not list an exam fee, passing score, or format. Do not budget from another state's numbers or from a prep company's claims.
6. Form your business entity. Most small plumbing companies use a limited liability company. An LLC is formed by filing Articles of Organization with the Maryland State Department of Assessments and Taxation (SDAT), Charter Division, for a $100 filing fee. You can file through Maryland Business Express. The name must include Limited Liability Company, L.L.C., LLC, L.C., or L C, and must not be misleadingly similar to another LLC, corporation, trade name, limited partnership or limited liability partnership on file with SDAT. Your resident agent must be a Maryland citizen over 18, a Maryland corporation, or a Maryland LLC with a Maryland street address. A P.O. box does not qualify. The agent must sign the Articles, and you must have the agent's consent before filing. If you want to hold a name while you prepare, a name reservation costs $25 and lasts 30 days. A corporation uses Articles of Incorporation and a $120 filing fee instead.
7. Choose a review speed. Standard LLC filings are reviewed during the second calendar month after submission, and paper filings take about 8 weeks. Expedited review costs an extra $50 and is completed in 7 to 14 business days. Online rush service costs an extra $325 and is reviewed within 3 hours when submitted by 2:30 p.m. on a business day. Same-day paper drop box service costs an extra $425. Pay for speed only if a contract or permit deadline requires it.
8. Register a trade name if you will operate under a different name. A trade name registration is filed with SDAT, not the county. The standard fee is $25, or $75 total with the $50 expedited fee. Use the SDAT form at https://dat.maryland.gov/SDAT%20Forms/nameappl.pdf.
9. Set up your tax accounts. Register with the Comptroller of Maryland through the Combined Registration Application on Business Express at https://businessexpress.maryland.gov/start/taxes-and-insurance. An LLC is a pass-through entity for state income tax, so members report income on their Maryland personal returns. The personal income tax is a graduated state rate of 2% to 6.5%, plus a county or Baltimore City local income tax of 2.25% to 3.30% for 2026. A corporation pays a flat 8.25% of Maryland taxable income. If any of your billing is for taxable goods or services, a sales tax permit may be required. The state sales tax rate is 6%, but confirm with the Comptroller whether your specific services or fixtures are taxable.
10. Calendar your recurring obligations. Every LLC and corporation must file the Annual Report and Business Personal Property Return (Form 1) with SDAT by April 15 each year. The fee is $300. If you need more time, the extension request is filed at pprextensions.dat.maryland.gov. Add your license renewal dates to the same calendar, because a lapsed license stops you from pulling permits even if your company is in good standing.

Do you need a trader's license?

There is no single general state business license in Maryland. Most businesses that sell goods need a trader's license from the Clerk of the Circuit Court in their county. The license year runs May 1 through April 30. If you only perform plumbing services, you may not need one. If you sell fixtures, supplies, or other goods over the counter, check with your county Clerk before you open for business. Growers and manufacturers are exempt. The Clerk needs a free Sales and Use Tax License from the Comptroller, obtained through the Combined Registration Application, before issuing a trader's license. The Clerk cannot issue one if you owe personal property tax or have missing SDAT filings, so keep your annual report current.

Common mistakes to avoid

• Forming the LLC before confirming the license class. The entity is easy to change later. Your license class and hour history determine which work you can legally perform from day one.
• Assuming a state license covers every job. Baltimore County and the WSSC area issue their own licenses and apply their own plumbing code. A state license alone may not get you through a permit in those areas.
• Reconstructing hours from memory. A log built at the end of several years rarely holds up. Sign off on hours as you earn them.
• Using a P.O. box for the resident agent. Maryland requires a Maryland street address for the resident agent, and a P.O. box does not meet that requirement.
• Filing a name that is too close to an existing one. Search the SDAT entity database first and reserve the name if you need time to finish your paperwork.
• Paying for expedited review you do not need. Standard LLC review takes about two months after submission. Plan around that timeline before paying $50 or $325 to speed it up.
• Missing the April 15 annual report. The $300 fee is due each year whether or not the business earned revenue. Set a reminder in February.
• Treating any figure in this guide as final. Fee schedules and deadlines change. Confirm each number with the agency that sets it before you file.

What to expect

A complete file, with signed hour logs and accurate entity paperwork, is more likely to move through review without a round of correction requests. That is the realistic goal of following this sequence. Business owners who handle the license and the entity in order often find that the bidding and permitting steps are easier to plan, because they know their license class and their entity status before they promise a timeline to a customer. The agencies do not guarantee their own timing, so build slack into your launch date, especially if you are waiting on the Board or on a standard LLC review.

Quick reference: where to confirm each figure

Task	Agency	Cost or deadline	Where to confirm
Plumbing or gas fitter license	Maryland State Board of Plumbing, Maryland Department of Labor	$18.50 to $150.50 (schedule effective July 1, 2025)	labor.maryland.gov
Baltimore County or WSSC license	Local authority	Confirm with the authority	Contact the county or WSSC directly
LLC formation	SDAT Charter Division	$100 filing fee	https://egov.maryland.gov/businessexpress
Name reservation	SDAT	$25 for 30 days	https://dat.maryland.gov/sdat%20forms/name_reservation.pdf
Trade name	SDAT	$25, or $75 with expedited fee	https://dat.maryland.gov/SDAT%20Forms/nameappl.pdf
Annual report	SDAT	$300, due April 15	https://dat.maryland.gov/businesses/Pages/default.aspx
Tax registration	Comptroller of Maryland	Varies by tax type	https://www.marylandcomptroller.gov/
Trader's license	Clerk of the Circuit Court in your county	Confirm with the Clerk; license year May 1 through April 30	Your county Clerk's office

This article is general information about Maryland business formation and plumbing licensing. It is not legal, tax, or licensing advice. Requirements change, and the figures here reflect the sources reviewed on October 14, 2026. Confirm every fee, deadline, and experience rule with the agency that administers it before you file. For complex situations, such as mixed residential and commercial work, multiple entities, or questions about personal liability, talk with a qualified Maryland attorney and a CPA.