Going out on your own
How to start a mechanical engineering firm in Ontario
Building-services mechanical engineers design the systems that make buildings habitable — HVAC, plumbing, and fire protection. As an MEP discipline, they work on the design side alongside architects, while the mechanical trades install what they specify.
Mechanical (Building Services) Engineer at a glance
- Credential
- P.Eng (PEO) — reserved title
- Path in
- Mechanical engineering degree → EIT → experience → NPPE → P.Eng
- Regulated by
- Professional Engineers Ontario (PEO)
- Insurance baseline
- Professional liability (E&O); a firm needs a Certificate of Authorization
- Professional body
- Professional Engineers Ontario (PEO)
You must be licensed first. A practice can only offer mechanical (building services) engineer services to the public once it holds the regulator’s firm authorization, which requires a licensed principal and professional liability insurance. Sort the firm authorization before you take work.
The steps to start your practice
- 1
Get a PEO Certificate of Authorization
A Certificate of Authorization lets your firm offer mechanical engineering to the public, with professional liability insurance in place — the gate to taking building-systems design work as a business.
Certificate of Authorization — PEO ↗ - 2
Incorporate (or form a professional corporation)
Most professionals incorporate to limit liability and for tax efficiency. Several regulated professions (architects, engineers) can form a professional corporation with a Certificate of Authorization — confirm the right entity type with your regulator before filing.
Full guide: Incorporation - 3
Set up your CRA accounts
Register for a Business Number, HST/GST (mandatory above $30,000 in revenue), payroll if you will hire, and corporate income tax. Professional service fees are HST-taxable.
Full guide: CRA Registration - 4
Carry professional liability (E&O) insurance
Errors & omissions insurance is the core coverage for a professional practice — and a firm-authorization condition for regulated professions. It protects against claims arising from your professional advice, designs, or certifications.
Full guide: Insurance - 5
Stand up your practice operations
Business banking, professional accounting, engagement letters and contracts, and the project and document workflows a practice runs on. This is the back office that keeps you paid and protected.
Full guide: Operational Setup
Your launch checklist
The whole page in one list.
- Get a PEO Certificate of Authorization
- Incorporate (or form a professional corporation)
- Set up your CRA accounts
- Carry professional liability (E&O) insurance
- Stand up your practice operations
Let AEC Stack handle the business side
Incorporation, CRA, insurance, and the operations to run a practice, set up so you can focus on the professional work.
Start your practice