How to Start a Plumbing Business in Colorado

The Master Plumber Requirement Comes First

Colorado doesn't let you operate a plumbing business on a journeyworker license alone. To register as a plumbing contractor with DORA, your business must designate an active, licensed Colorado master plumber as its "Responsible Master" — the qualifying agent who takes professional responsibility for the company's plumbing work.

That master plumber must be a full-time, W-2 employee of the company. They can only serve as the responsible master for one contractor at a time. If you're the master plumber and the business owner, you fill both roles. If you're a journeyworker who wants to start a company, you'll need to either earn your master license first or hire someone who already holds one.

This is a hard prerequisite — there's no workaround, and DORA won't process your contractor registration without it.

Form Your Business Entity

Before registering with DORA as a contractor, you need a legally formed business entity. Most plumbing companies in Colorado register as LLCs through the Colorado Secretary of State. The process is straightforward:

• LLC filing fee: $50 (one-time)
• Trade name (DBA) registration: $25 (optional, if you're operating under a name different from the LLC's legal name)
• Periodic report: $25 annually to maintain good standing

Your business must have an active Certificate of Good Standing from the Secretary of State before DORA will accept the contractor registration application. If the SOS shows your entity as delinquent or dissolved, the contractor application will be rejected.

Register as a Plumbing Contractor with DORA

With your business entity formed and your master plumber designated, you can apply for contractor registration through DORA's MyLicense portal. The registration package requires:

• The $210 contractor registration fee
• Your designated master plumber's active license number
• A signed Acknowledgment of Responsibility form
• Proof of your Secretary of State good standing
• Commercial general liability insurance documentation
• Workers' compensation coverage (or a filed exemption)

The contractor registration renews every 24 months. This is a business-level credential — completely separate from the individual master plumber license, which follows its own renewal cycle.

Insurance and Workers' Compensation

Colorado plumbing contractors need commercial general liability insurance. Specific coverage minimums vary by municipality (Denver, Boulder, PPRBD, and others each set their own thresholds). Carrying at least $1,000,000 per occurrence covers the highest per-occurrence example listed above, but verify each jurisdiction's required aggregate and other certificate terms before applying.

Workers' compensation is where Colorado gets particularly strict. Under CDLE rules, LLC members and corporate officers are legally classified as employees. If you're a sole-member LLC, you either carry workers' compensation coverage or file a formal exemption. To qualify for the exemption, you must own at least 10% of the company, hold an officer title, and file the formal rejection of coverage online through CDLE.

Operating without required coverage isn't a gray area — it can result in fines of up to $500 per day and business shutdown orders.

Display and Branding Requirements

Effective June 30, 2025, Colorado requires all registered plumbing contractors to display their registration number and their designated master plumber's license number on:

• All service vehicles — at least two locations, in lettering at least two inches high
• All documents — bid sheets, contracts, invoices, and billing statements
• Your website — homepage, about page, contact page, and any digital advertising

If your registration number or responsible master changes, you have 90 days to update all physical and digital displays. Non-compliance can trigger disciplinary action from DORA.

Local Municipal Registrations

Your state contractor registration doesn't automatically authorize you to work in any specific city or county. Colorado's Home Rule system means municipalities control their own contractor registrations, permits, and inspections. Before you take jobs in a new jurisdiction, you'll need to register with the local building department.

The major jurisdictions each have their own requirements, fees, and insurance thresholds. Budget for multiple local registrations if you plan to work across the Front Range — Denver, Boulder, Colorado Springs (PPRBD), and surrounding areas all maintain independent systems.

The 20-Day Rule

Once your contractor business is running, the biggest operational vulnerability is losing your designated master plumber. If your master leaves, loses their license, or is otherwise unavailable, your contractor registration immediately enters "Need Master Hire — Cannot Practice" status.

You have exactly 20 days to hire another licensed Colorado master plumber and file a new Acknowledgment of Responsibility with DORA. If you miss that deadline, all plumbing operations stop — no bidding, no permitting, no active work.

Planning for this contingency from day one is worth the effort. Some contractors maintain relationships with semi-retired masters who could step in as an interim qualifying agent if needed.

Building Your Cost Model

Between state fees, local registrations, insurance premiums, and ongoing renewals, the total startup cost for a Colorado plumbing business runs significantly higher than the $210 DORA registration fee alone. The Colorado Plumber License Guide breaks down every fee across state and major municipal jurisdictions, so you can build an accurate financial plan before you commit to the overhead.

See more Colorado guides →