HAWAII · plumber
C-37 Plumbing Contractor
Hawaii Department of Commerce and Consumer Affairs — Contractors License Board (Professional and Vocational Licensing Division) →Scope of Work
A C-37 Plumbing Contractor is authorized to install, repair, or alter complete plumbing systems, including supply water piping systems, hot water piping systems (including heat pump water heaters and hot water supply boilers with a heat input of 200,000 BTU/h or less), waste water piping systems, fuel gas piping systems, waste water treatment systems, and other fluid piping systems; the equipment, backflow prevention assemblies, instrumentation, non-electric controls, and fixtures for these systems; piping for vacuum, air, and medical gas systems; spas and swimming pools; lawn sprinkler systems; irrigation systems; sewer lines within property lines; fire protection sprinkler systems when supervised by licensed mechanical engineers or licensed fire protection contractors; and solar hot water heating systems. Source: Description of Contractor License Classifications, Hawaii Administrative Rules Title 16 Chapter 77, Exhibit A (https://cca.hawaii.gov/wp-content/uploads/2026/01/DescriptionofContractorLicenseClassifications-1.pdf).
Two-License Structure
Hawaii separates the contractor license from the individual plumber license. The C-37 authorizes the business to contract for plumbing work; the individual performing the work still needs a plumber license (PM Master Plumber, PJ Journey Worker Plumber, or PA Plumber's Apprentice) under HRS Chapter 448E, administered by the Hawaii Board of Electricians and Plumbers. A firm that holds a C-37 but whose RME does not personally hold an individual plumber license must employ a licensed plumber to actually perform the plumbing work. Source: Hawaii Contractor Entity Application, page 6 (https://cca.hawaii.gov/wp-content/uploads/2026/01/Require-App-for-Contractor-Entity_10.25.pdf).
Experience and Training
Four years of supervisory experience within the past ten years within the scope of the requested classification, documented on the application. Applicants must designate a Responsible Managing Employee (RME), who is an officer, partner, or member of the contracting entity with full-time supervisory authority. Source: Hawaii Contractor Entity Application (https://cca.hawaii.gov/wp-content/uploads/2026/01/Require-App-for-Contractor-Entity_10.25.pdf).
Exam
Two exams are required: (1) the Business and Law exam and (2) the C-37 Trade exam. Both are administered by the Board's designated testing vendor after Board approval of the application. Exam dates are published on the Board's Application Deadline and Examination Dates page (https://cca.hawaii.gov/pvl/boards/contractor/application-deadline-examination-dates/).
Insurance
Applicants must submit a certificate of liability insurance showing Bodily Injury Liability of at least $100,000 each person and $300,000 each occurrence, and Property Damage Liability of at least $50,000 each occurrence, and a certificate of workers' compensation insurance (a prescribed form may substitute for single-member LLCs or for corporations where the RME owns at least 50% and there are no other employees). Failure to maintain continuous liability and workers' compensation coverage causes automatic forfeiture of license. Source: Hawaii Contractor Entity Application, page 6 (https://cca.hawaii.gov/wp-content/uploads/2026/01/Require-App-for-Contractor-Entity_10.25.pdf).
GE Tax License
A contractor doing business in Hawaii must register for the Hawaii General Excise (GE) tax with the Department of Taxation. The GE tax applies to gross receipts from construction activity in Hawaii. Source: Hawaii Department of Taxation, General Excise Tax (https://tax.hawaii.gov/geninfo/get/).
Reciprocity
Hawaii's Contractors License Board does not currently maintain published contractor-to-contractor reciprocity agreements with other states. Out-of-state applicants apply through the same entity or sole-owner application; the Board evaluates the applicant's prior licensing and experience on a case-by-case basis.
Renewal Cycle
All Hawaii contractor licenses renew by September 30 of each even-numbered year (biennial renewal), regardless of issuance date. Licenses not renewed by September 30 are forfeited; restoration is accepted through November 30 of the even-numbered year with a penalty fee. After November 30, restoration is not accepted and a new application is required. Source: Hawaii Contractor Entity Application, page 7 (https://cca.hawaii.gov/wp-content/uploads/2026/01/Require-App-for-Contractor-Entity_10.25.pdf).