Colorado Plumbing Contractor Vehicle Display Requirements

The Display Mandate Is State Law

Effective June 30, 2025, Colorado enforces strict display and branding requirements for all registered plumbing contractors under C.R.S. § 12-155-125. This isn't a suggestion or a best practice — it's a statutory obligation that applies to every registered plumbing contractor in the state.

The requirement is straightforward: you must display your contractor registration number and the license number of your designated master plumber across all company-facing assets. The specifics of where and how are more detailed than most contractors initially realize.

Vehicle Requirements

All company-owned or business-use vehicles must display both numbers — your contractor registration number and your responsible master's license number — in at least two locations on each vehicle. The lettering must be at least two inches in height.

This applies to every vehicle your company uses for plumbing work, not just the primary truck. If an apprentice drives a company van to a job site, that van needs the numbers displayed. The intent is to make identification possible during job-site inspections, where inspectors verify contractor credentials as part of their compliance checks.

Use a legible display that meets the required size and placement rules; confirm any sign format with DORA if you're unsure.

Document Requirements

Both numbers must appear on all:

• Bid sheets — any written estimate or proposal you submit to a potential customer
• Contracts — all service agreements and project contracts
• Invoices — every bill you send
• Billing statements — any payment-related correspondence

If you use a digital invoicing system or proposal software, add the numbers to your templates so they appear automatically. For handwritten estimates (common for small residential jobs), include the numbers in your standard form header.

Website and Digital Advertising

Your contractor registration number and master plumber license number must be displayed on:

• Your website's homepage
• Your About Us page
• Your Contact Us page
• Any digital or social media advertising

That last point catches some contractors off guard. If you run Facebook ads, Google Business Profile posts, or any other paid digital promotion, the display requirement applies. The practical implementation varies by platform — most contractors add the numbers to their profile descriptions and ensure they're visible on their website, which is typically linked from any ad.

The 90-Day Update Rule

If your contractor registration number changes or you designate a new responsible master plumber, all physical and digital displays must be updated within 90 days. This applies to vehicles, printed materials, website pages, and advertising.

A master plumber departure triggers this clock. If your business designates a new master (you have 20 days to do so, or operations halt), you then have 90 days from the change to update every display point. Plan for both timelines to overlap — the 20-day hiring urgency and the 90-day display update deadline.

Enforcement and Consequences

Non-compliance with the display requirements can result in disciplinary action from DORA, ranging from administrative fines to license revocation. Job-site inspectors can check vehicle displays during any standard inspection, and consumer complaints about missing identification numbers are handled through DORA's complaint process.

The display requirements serve a public protection function — they make it possible for property owners, general contractors, and inspectors to quickly verify that the plumber on-site is working for a legitimately registered contractor. Compliance is simple once your systems are set up, and the Colorado Plumber License Guide covers the full set of contractor compliance obligations alongside the licensing and registration process.

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