Is professional liability insurance mandatory for engineers in Ontario?

For holders of a Certificate of Authorization, effectively yes. Section 74 of Regulation 941 requires a policy with at least $250,000 per claim and a $500,000 aggregate or automatic reinstatement. A holder can instead qualify for one of the listed exemptions, or tell each client before contracting that it is not insured to the minimum and get the client's written authority to proceed.

What other terms does Ontario's Regulation 941 set for engineering E&O?

Beyond the limits, the deductible cannot exceed the greater of $5,000 or 5% of fees billed in the 12 months before the policy was issued. The policy must cover all professional engineering services offered to the public, require 45 days' written notice before a non-compliant cancellation or change, or 15 days for non-payment, and be placed with a sufficiently capitalized insurer or Lloyd's.

Do engineers in other provinces have to carry insurance?

It depends on the province. Each province and territory regulates engineering through its own association, and the insurance rules are not the same as Ontario's. Confirm the current requirement directly with your association before you rely on any summary. Client contracts will often set a higher bar than any regulator in any case.

Why do structural and geotechnical engineers pay more for E&O?

Because their errors are expensive to fix. A structural or foundation problem can mean demolition, delays, relocation of occupants and claims from several parties at once, and it may surface years after completion. Underwriters therefore rate those disciplines above most mechanical, electrical or advisory work, and clients usually ask them for higher limits as well.

Does my firm's E&O cover me if I stamp work on the side?

Usually not. A firm policy generally covers employees for work done for the firm. Reviews or stamps done independently, for friends or for another company, fall outside it. Independent work may also need its own Certificate of Authorization in Ontario, which brings the section 74 insurance requirement with it. Arrange separate cover before taking on side work.

My contract says I must keep E&O for two years after completion. What does that mean?

Because E&O is claims-made, a claim is covered only if a policy is in force when it is made. Keeping cover for two years after completion means renewing continuously, with the same retroactive date, for at least that period. If you plan to retire or close, you would need an extended reporting period to meet the term.

Does E&O cover pollution claims from environmental work?

Often not fully. Many professional liability forms exclude pollution, which matters if you do site assessments, remediation design or testing on contaminated land. Environmental and geotechnical firms usually need E&O written without that exclusion or a separate pollution liability policy. Check the wording before you accept environmental work, not after a claim arrives.

Do I need general liability if I have E&O?

Yes, if you or your staff visit sites. E&O covers financial loss from your engineering services. Injury to someone else, or damage to a client's property during a site visit, test or inspection, is a general liability claim. Owners and contractors also routinely ask to be named as additional insureds on your CGL, which E&O cannot provide.

How is engineering insurance priced?

E&O is rated mainly on fees split by discipline and project type, the size of your largest contracts, any U.S. work, the limit and deductible, whether defence costs sit inside the limit, and claims history. Written agreements with limitation of liability clauses help. CGL and equipment are rated on site activity, instrument values and vehicles, and cyber on records held and controls.

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In short

An engineering firm in Canada needs professional liability (E&O) for design and advice errors, general liability for site work, cyber and an office package. In Ontario, a holder of a Certificate of Authorization must carry E&O of at least $250,000 per claim under section 74 of Regulation 941, qualify for an exemption, or get each client's written consent to work uninsured. Structural and geotechnical work usually needs higher limits than the minimum.

Last reviewed October 26, 2026

Minimum E&O per claim for Ontario Certificate of Authorization holders, with $500K aggregate or automatic reinstatement (Reg. 941, s. 74): $250K; Minimum E&O per claim for Ontario Certificate of Authorization holders, with $500K aggregate or automatic reinstatement (Reg. 941, s. 74)
Written notice required before an Ontario engineering E&O policy is cancelled or amended out of compliance (15 for non-payment): 45 days; Written notice required before an Ontario engineering E&O policy is cancelled or amended out of compliance (15 for non-payment)
Minimum professional liability per claim in the CCDC 31 (2020) owner and consultant agreement: $2M; Minimum professional liability per claim in the CCDC 31 (2020) owner and consultant agreement
Canadian insurers we compare for engineering firms: 17; Canadian insurers we compare for engineering firms

An engineer's seal certifies judgement, and the claims against it are severe: a cracked slab, a flooded excavation, a building that cannot hold temperature. They often arrive years after completion, through a contractor who brings the design team into an owner's suit. In Ontario, firms holding a Certificate of Authorization must meet the insurance rules in section 74 of Regulation 941, and most contracts ask for far more than that minimum. Our professional liability guide explains claims-made cover in detail.

We build engineering programs around your disciplines and your contracts: E&O with protected retroactive dates, excess or project limits where a contract requires them, general liability for site work, pollution cover for environmental and geotechnical firms, equipment, cyber and an office package. The wider picture for advice-based firms is on our business and professional services page.

What the package includes

Professional liability (E&O) that meets Regulation 941 in Ontario
Excess and project-specific E&O for large contracts
Commercial general liability for site visits, testing and inspections
Pollution liability for environmental and geotechnical work
Survey instruments, testing equipment and field laptops
Cyber liability for models, drawings and client data
Office contents and business interruption
Commercial and non-owned auto for field staff

Engineering insurance by discipline

Every engineering firm needs E&O, but disciplines carry very different severity. A miscalculated beam or an unexpected soil condition can mean demolition, delay and a building that cannot be occupied. A missed spec in a lighting layout usually costs far less. Underwriters price that difference, and limits should reflect it. The wider picture for advice-based firms is on our business and professional services page.

How exposure differs across engineering disciplines
Discipline	Typical claim source	Program focus
Structural	Design or calculation errors, inadequate review of shop drawings, failures found during or after construction	Higher E&O limits, long continuity, careful scope wording on field review
Geotechnical	Soil and groundwater conditions that differ from the report, foundation settlement, shoring failures	Higher limits, clear limitations in reports, pollution exposure where testing involves contamination
Civil and municipal	Drainage, grading and road design errors, flooding of neighbouring property	E&O plus CGL for site presence, third-party property damage
Mechanical and electrical	HVAC that cannot hold temperature, undersized services, energy model shortfalls	E&O with cover for commissioning and site review
Environmental	Missed contamination in a site assessment, remediation design that fails	E&O with pollution coverage, since many E&O forms exclude pollution
Industrial, process and software	Production downtime, control system failures, equipment that does not perform	E&O written for the industry served, often with technology E&O and cyber

The coverages an engineering firm needs

Professional liability (E&O): defence and damages when a client or third party alleges your design, report, review or advice was negligent. Claims-made, so retroactive dates and continuous cover decide whether old projects stay protected.
Excess or project-specific E&O: for contracts that require more than your annual limit. Some owners arrange one policy for the whole design team on a large project.
Commercial general liability: injury to others and damage to their property during site visits, testing and inspections. E&O does not cover a dropped instrument through a skylight.
Pollution liability: for environmental and geotechnical work. Check whether your E&O has a pollution exclusion before you take on site assessments.
Tools and equipment: survey instruments, testing gear, drones and field laptops, insured wherever they are.
Office package with business contents and business interruption, plus cyber for models, drawings and client data.
Commercial auto for field vehicles, and non-owned auto for staff driving their own cars to sites.

Ontario: what Regulation 941, section 74 requires

In Ontario, a Certificate of Authorization is what allows a business to offer and provide professional engineering services to the public. Section 74 of Regulation 941 under the Professional Engineers Act sets the insurance that goes with it. A holder must carry professional liability insurance that meets these minimums:

Minimum terms for an Ontario engineering E&O policy under Reg. 941, s. 74 (1)
Term	Minimum requirement
Limit	Not less than $250,000 for each claim, plus either a $500,000 annual aggregate or an automatic limit reinstatement feature
Deductible	No more than the greater of $5,000 or 5% of the fees billed in the 12 months before the policy was issued
Scope	Errors, omissions and negligent acts in all professional engineering services offered or provided to the public, on terms consistent with normal industry practice
Cancellation	At least 45 days' written notice before a cancellation or change that breaks compliance, or 15 days for non-payment of premium
Insurer	An insurer with aggregate capital and surplus of at least $20,000,000, or Lloyd's underwriters

Section 74 (2) gives four ways out of the requirement. The holder is participating in the Ontario Association of Architects' Indemnity Plan and practises only within that plan. Substantially all claims would be covered by other insurance on terms not materially less than the minimum. The insurance would relate to pollution, nuclear, aviation or shipping hazards. Or, before signing an agreement, the holder tells each client it is not insured to the minimum and gets the client's written authority to proceed, using PEO's form and signed by the holder or an officer, director or partner.

The disclosure route is legal, but it is a hard sell to most commercial and public clients, and it leaves the firm funding its own defence. For most practices the minimum is also far below what contracts demand.

Engineers outside Ontario

Each province and territory regulates engineering through its own association, and its insurance rules may look nothing like Ontario's section 74. We have not summarized each province here, because the rules change and the details matter. Confirm the current requirement with your association before relying on any summary, including ours.

If you practise in more than one province, or design for projects in the United States, tell us where each project is. A policy territory or jurisdiction limit can exclude a suit brought where the project sits, even if your office is in Canada.

Firm policy or personal cover: the stamp question

A firm's E&O generally covers employees for work they do for the firm. It does not usually follow an engineer who reviews drawings for a friend, stamps work for another company, or runs a side practice. In Ontario that side work may also need its own Certificate of Authorization, and with it the insurance in section 74.

The same gap appears when engineers leave. Claims about projects you worked on can still name you personally, years after you moved firms. Ask your former employer whether its policy still covers former staff for past work, and keep a copy of the answer.

Long-tail claims and the limitation clock

Engineering defects are often hidden until a building settles, a slab cracks or a system fails under peak load. Ontario's Limitations Act, 2002 sets a basic two-year period from when a claim is discovered and an ultimate 15-year period from the act or omission. For buildings and infrastructure, discovery can start long after the engineer's last site visit.

Contribution claims add another layer. When an owner sues a contractor, the contractor commonly brings in the design consultants. In a 2026 decision, Lower William Properties v. Santaguida, the Court of Appeal for Ontario declined to finally decide whether the 15-year ultimate period limits every kind of contribution claim. The case involved an architect, but the same question affects anyone who worked on a project. Keep cover continuous and keep project files long after completion.

The claims that actually happen (hypothetical scenarios)

These hypothetical scenarios show which policy responds. They are illustrations, not cost estimates.

Hypothetical engineering claims and the policy that responds
Scenario	Allegation	Policy that responds
A warehouse floor slab cracks under racking loads two years after occupancy	The structural design did not account for the specified racking	E&O; the owner sues the contractor, who adds the engineer as a third party
Groundwater floods an excavation during construction	The geotechnical report understated water levels	E&O, for delay and remediation costs claimed by the contractor and owner
A new office building cannot hold temperature in summer	Mechanical design was undersized	E&O, for redesign and replacement equipment
A field technician's tripod damages a client's finished floor	Property damage during a site visit	CGL
A Phase I site assessment misses a former fuel tank	Negligent environmental assessment, plus cleanup costs	E&O for the assessment, pollution liability for the contamination claim if the E&O excludes it

Client contracts, CCDC forms and certificates

CCDC 31 (2020) is the Canadian standard agreement between an owner and a consultant, adapted from the ACEC 31 engineering agreement. As summarized by Osler, it requires the consultant to carry professional liability of at least $2,000,000 per claim, maintained from the start of the services until two years after completion, and to require similar cover from subconsultants. It also calls for CGL and automobile liability. It caps the consultant's liability for losses not covered by the required insurance at the greater of $250,000 or the consultant's fee and expenses, with exceptions for third-party injury and property damage.

Post-completion periods: on a claims-made policy, "maintain for two years after completion" means keeping continuous cover, or buying an extended reporting period, for that time.
Indemnities: most E&O policies exclude liability you assume by contract beyond your duty of care. Negotiate indemnities back to a negligence standard.
Standard of care: avoid fitness-for-purpose or performance guarantees, especially on design-build and process work.
Additional insureds: owners can usually be added to your CGL as an additional insured, but not to your E&O.
Certificates: owners and contractors want proof before work starts. See why every contract asks for a certificate.

If you work for design-builders or general contractors, our construction and contractors package explains the insurance they carry and what they will ask of you.

What engineer insurance costs: the rating logic

Engineering E&O is rated on fees and on what those fees are for. Underwriters ask for revenue split by discipline and project type, because structural and geotechnical work rates above mechanical or electrical design, and condominiums and infrastructure rate above routine commercial work.

Discipline and project mix, including any condominium, bridge, dam or U.S. work.
Fees, largest contracts and the share of work as a subconsultant.
Limits, deductible and whether defence sits inside the limit.
Claims and circumstances over the past five or more years.
Contract practice: written agreements, limitation of liability clauses and quality review.
For CGL and equipment: site time, testing activities, instrument values and vehicles.

The market is softer than it has been. Marsh's Global Insurance Market Index put Canadian financial and professional lines rates down 4% in the third quarter of 2026. Our professional liability guide explains how limits and defence costs interact.

How we build an engineering insurance program

1Map the practice: disciplines, project types, provinces, any U.S. work, and the entity that signs contracts.
2Check the regulator: in Ontario we confirm the policy meets section 74 of Regulation 941; elsewhere we confirm the current rule with you and your association.
3Read the contracts: we review your standard agreement and live projects for E&O limits, post-completion periods and indemnities.
4Protect the history: we confirm retroactive dates and prior circumstances so past projects keep their cover when you renew or move.
5Market it: we take a full submission to the insurers on our panel of 17 whose appetite fits your disciplines, and compare wordings, not just premiums.
6Keep it current: certificates as projects start, limits that grow with fees, and run-off planned before you retire, sell or merge.

Working alongside architects? See our architect insurance guide for how their mandatory program fits with yours, or request a quote.

Good to know

Frequently asked questions

Is professional liability insurance mandatory for engineers in Ontario?: For holders of a Certificate of Authorization, effectively yes. Section 74 of Regulation 941 requires a policy with at least $250,000 per claim and a $500,000 aggregate or automatic reinstatement. A holder can instead qualify for one of the listed exemptions, or tell each client before contracting that it is not insured to the minimum and get the client's written authority to proceed.
What other terms does Ontario's Regulation 941 set for engineering E&O?: Beyond the limits, the deductible cannot exceed the greater of $5,000 or 5% of fees billed in the 12 months before the policy was issued. The policy must cover all professional engineering services offered to the public, require 45 days' written notice before a non-compliant cancellation or change, or 15 days for non-payment, and be placed with a sufficiently capitalized insurer or Lloyd's.
Do engineers in other provinces have to carry insurance?: It depends on the province. Each province and territory regulates engineering through its own association, and the insurance rules are not the same as Ontario's. Confirm the current requirement directly with your association before you rely on any summary. Client contracts will often set a higher bar than any regulator in any case.
Why do structural and geotechnical engineers pay more for E&O?: Because their errors are expensive to fix. A structural or foundation problem can mean demolition, delays, relocation of occupants and claims from several parties at once, and it may surface years after completion. Underwriters therefore rate those disciplines above most mechanical, electrical or advisory work, and clients usually ask them for higher limits as well.
Does my firm's E&O cover me if I stamp work on the side?: Usually not. A firm policy generally covers employees for work done for the firm. Reviews or stamps done independently, for friends or for another company, fall outside it. Independent work may also need its own Certificate of Authorization in Ontario, which brings the section 74 insurance requirement with it. Arrange separate cover before taking on side work.
My contract says I must keep E&O for two years after completion. What does that mean?: Because E&O is claims-made, a claim is covered only if a policy is in force when it is made. Keeping cover for two years after completion means renewing continuously, with the same retroactive date, for at least that period. If you plan to retire or close, you would need an extended reporting period to meet the term.
Does E&O cover pollution claims from environmental work?: Often not fully. Many professional liability forms exclude pollution, which matters if you do site assessments, remediation design or testing on contaminated land. Environmental and geotechnical firms usually need E&O written without that exclusion or a separate pollution liability policy. Check the wording before you accept environmental work, not after a claim arrives.
Do I need general liability if I have E&O?: Yes, if you or your staff visit sites. E&O covers financial loss from your engineering services. Injury to someone else, or damage to a client's property during a site visit, test or inspection, is a general liability claim. Owners and contractors also routinely ask to be named as additional insureds on your CGL, which E&O cannot provide.
How is engineering insurance priced?: E&O is rated mainly on fees split by discipline and project type, the size of your largest contracts, any U.S. work, the limit and deductible, whether defence costs sit inside the limit, and claims history. Written agreements with limitation of liability clauses help. CGL and equipment are rated on site activity, instrument values and vehicles, and cyber on records held and controls.

Sources

R.R.O. 1990, Reg. 941 under the Professional Engineers Act (s. 74, professional liability insurance). Government of Ontario, e-Laws, Current consolidation.
Application for Renewal of Certificate of Authorization (liability insurance, Regulation 941, ss. 47 and 74). Professional Engineers Ontario, Form dated July 2010.
CCDC 31 (2020): a new consultant contract. Osler, Hoskin & Harcourt LLP, April 1, 2021.
Limitations Act, 2002, S.O. 2002, c. 24, Sched. B (ss. 4 and 15). Government of Ontario, e-Laws, Current consolidation.
Architects move closer to protection from litigation after 15 years (Lower William Properties v. Santaguida, 2026 ONCA 581). Pro-Demnity Insurance Company, October 20, 2026.
Canada commercial insurance rates fall for third straight year (Marsh Global Insurance Market Index, Q3 2026). Insurance Business Canada, October 21, 2026.

This page is general information, not insurance or legal advice. Coverage depends on your policy wording and the insurer. Speak with a licensed broker about your situation.

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