Colorado Plumber License Requirements: Complete State and Local Guide

Colorado regulates plumbing through a dual-layer system that trips up even experienced tradespeople. The Department of Regulatory Agencies (DORA) handles your individual competency license — apprentice, residential, journeyworker, or master — while cities and counties control who actually pulls permits and starts work. Missing either layer means you can't legally turn a wrench on a job site.

Here's the full picture of what each license tier requires and how the pieces fit together.

The Four License Tiers and What Each One Demands

DORA's State Plumbing Board administers four individual credential levels. Each builds on the one below it, with progressively more field hours and a harder exam:

Registered Apprentice — Your employer must register you with DORA within 30 days of your hire date. The fee is $30. You'll get a physical registration card that you're required to carry on every job site, because inspectors can (and do) check credentials during routine visits. No exam is required, but you work exclusively under the direct supervision of a licensed plumber.

Residential Plumber — Requires 3,400 hours of documented experience (roughly two years of full-time work at DORA's rate of 163 hours per month). You must pass the PSI residential exam with a score of at least 70%. The application fee is $100. This license limits you to one- to four-family dwellings, two stories max. If you want to work a commercial job site, you'd need to maintain an active apprentice registration and work under supervision.

Journeyworker Plumber — Requires 6,800 hours (about four years full-time). The exam passing threshold is 70%, and the application fee is $120. This is the tier that removes the residential-only restriction — you can work across residential, commercial, and industrial projects. Note the title change: as of July 1, 2025, House Bill 24-1344 officially replaced "Journeyman" with "Journeyworker" throughout the Plumbers Practice Act.

Master Plumber — Requires 8,500 hours (about five years full-time), including at least one year holding an active Journeyworker license. The exam demands a higher 75% passing score, and the application fee is $140. This is the only individual credential that qualifies you to serve as a contractor's designated master — the person whose license authorizes the business to operate.

The Contractor Registration Layer

An individual license — even a master — doesn't authorize you to contract for plumbing work, bid on projects, or pull municipal permits. For that, you need a separate Plumbing Contractor registration from DORA, which costs $210.

The business must designate an active Colorado-licensed Master Plumber as its "Responsible Master," and that person must be a full-time W-2 employee. They can serve as the qualifying master for only one contractor at a time. If your designated master leaves or loses their license, you have exactly 20 days to hire a replacement or DORA suspends your registration — meaning all plumbing operations, bids, and permitting stop.

Before applying, you also need:

• A Colorado Secretary of State business registration with a Certificate of Good Standing ($50 LLC filing fee)
• Commercial general liability insurance (most municipalities require $600,000 to $1,000,000 per occurrence)
• Workers' compensation coverage for all employees (corporate officers who own at least 10% can file a formal rejection, but the default is mandatory coverage)

Experience Verification: The Part Most People Underestimate

DORA calculates experience using a fixed formula: one month of full-time work equals 163 hours. All experience must be verified by a supervising Master Plumber or registered plumbing contractor — you cannot verify your own hours, period. If a previous employer is unreachable, co-owners or office managers can sign on company letterhead, and DORA's annual apprentice reporting database (which contractors must update every January 1) can serve as backup verification.

Trade school graduates from accredited two-year programs can offset up to 2,000 hours of field requirements, with one classroom hour equaling one field hour. Military plumbing experience is credited at one month of field time for every six months of documented military training, capped at one year.

The Exam Process

Colorado uses an "exam-first" system — you schedule and pass the PSI exam before applying to DORA, not after. Book through PSI Services four to six weeks ahead of your preferred date. The exam covers the International Plumbing Code (IPC), International Fuel Gas Code (IFGC), and State Plumbing Board Rules. Spanish-language versions are available.

On test day, bring a valid government-issued photo ID with your signature (military IDs aren't accepted by PSI). No personal items or electronics are allowed in the testing room. Once you pass, you'll receive a score report at the testing center, which you'll include in your DORA application package along with your notarized experience affidavits.

Municipal Registration and Permits

Even with a state contractor registration in hand, you still need to register with each local building department before starting work. Colorado is a Home Rule state, which means municipalities maintain full control over local contractor registration, permits, and inspections.

Denver requires a Contractor License Application, a Supervisor Statement of Responsibility, and a copy of your state plumbing contractor card — all submitted at the Wellington Webb Municipal Office Building. The Pikes Peak Regional Building Department covers El Paso and Teller counties with its own registration system and fees. Boulder County requires $600,000 per occurrence in general liability, while the City of Boulder sets the bar at $1,000,000.

The pattern is consistent: register locally, prove your state credentials, show insurance, pay the local fee, then pull permits project by project.

What Comes Next

If you're mapping out your full path from apprentice registration through contractor setup — including the experience documentation templates, municipal registration checklists, and the complete fee schedule across major Colorado jurisdictions — the Colorado Plumber License Guide walks through every step in sequence. It's built around the same dual-layer system covered here, with fillable trackers for hours, affidavits, and local registrations so nothing falls through the cracks.

See more Colorado guides →