New Hampshire HVAC LLC Formation

Two Registrations for Fuel-Gas or Plumbing Work

Forming an HVAC LLC that will perform fuel gas fitting or plumbing in New Hampshire requires registering with two entirely separate agencies, in a specific order. Most technicians know about the Secretary of State filing. Fewer realize they also need an OPLC Mechanical Business Entity license before they can legally bid, advertise, or pull permits for that work under their business name.

Skipping either one creates real problems. An LLC without the OPLC business entity license can't pull fuel-gas or plumbing permits — municipalities check OPLC business credentials before issuing those permits. An OPLC business entity without the SOS registration isn't legally formed as a corporate entity, which means the liability protection you wanted from the LLC doesn't exist.

Step 1: Secretary of State LLC Filing

Register your LLC through the New Hampshire Secretary of State's QuickStart portal. The filing fee is $102 online or $100 by mail.

You'll need to provide:

• LLC name (must include "LLC" or "Limited Liability Company")
• Registered agent and office address in New Hampshire
• Managing member information
• Nature of business (mechanical contracting, HVAC services, or similar)

Processing time for online filings is typically a few business days. Once approved, you'll receive a Certificate of Formation.

If you'll operate under a trade name different from your legal LLC name — common for HVAC businesses that want a customer-facing brand — file a Trade Name Registration (DBA) with the Secretary of State for an additional $50.

Step 2: Federal EIN

After SOS approval, obtain a Federal Employer Identification Number from the IRS website. This is free and issued immediately online. You'll need the EIN for your business bank account, insurance applications, and OPLC business entity application.

Step 3: Insurance Before OPLC

The OPLC won't process your business entity application without proof of commercial general liability insurance. The practical minimum is $1,000,000 per occurrence.

Here's the piece that catches almost every new single-member HVAC LLC: workers' compensation insurance. Under RSA 281-A, forming an LLC immediately classifies the managing members as employees of the entity. New Hampshire allows LLCs with three or fewer members to file an exclusion from workers' comp coverage — but that exclusion is legally voided if the member performs physical, on-site manual labor at any active construction site.

Since virtually all residential and commercial HVAC work happens on active construction or renovation sites, a solo HVAC technician operating as an LLC cannot legally exclude themselves from workers' comp. You need an active policy covering yourself before your first job.

The penalty for operating without required workers' comp is up to $2,500 per infraction plus $100 for every business day you operate uncovered. The Department of Labor enforces this independently from the OPLC.

Step 4: OPLC Mechanical Business Entity License

Submit the Mechanical Business Entity Initial and Renewal Application to the OPLC. The application requires:

• Proof of SOS registration
• Designation of a qualifying license holder (a licensed gas fitter or master plumber who will be legally responsible for all mechanical operations)
• Proof of commercial general liability insurance
• $250 application fee

The qualifying party must hold an active, individual OPLC license. If you're a sole operator with your own gas fitter license, you designate yourself.

The sole-licensee fee exemption: If you're the only licensed professional in the entity and employ no other licensed technicians, apprentices, or trainees, you're exempt from the $250 fee under Mec 307.04(g). This exemption saves significant startup costs for solo operators but ends the moment you hire any licensed staff.

Step 5: State Tax Registrations

New Hampshire has no income tax or sales tax, but businesses face two relevant taxes:

• Business Profits Tax (BPT): 7.5% on gross business income exceeding $109,000
• Business Enterprise Tax (BET): 0.55% on the total enterprise value tax base

Register with the New Hampshire Department of Revenue Administration. Both taxes are filed annually. The BET is credited against BPT liability, so you're not paying both in full.

The Complete Startup Sequence

The correct order matters because each step depends on the previous one:

1. Pass your trade examination ($100)
2. Apply for individual OPLC license ($190)
3. File LLC with Secretary of State ($102)
4. Get EIN from IRS (free)
5. Secure insurance (general liability + workers' comp)
6. Apply for OPLC Mechanical Business Entity license ($250, or exempt if sole licensee)
7. Register with DRA for business taxes
8. Pull your first municipal permit

The New Hampshire HVAC License Guide walks through each step with the specific forms, timelines, and documentation checklists so nothing gets submitted out of order.

See more New Hampshire guides →