CNESST and WSIB Coverage for Temporary Workers: What Clients Need to Verify

When a temporary worker is injured at your facility, two questions determine who pays: who is the worker's employer of record, and does that employer have active workers' compensation coverage?

If the answers are "the staffing agency" and "yes," the claim is processed through the agency's account. If the answer to either question is unclear or negative, you — the client company — may be held liable for the full cost of the claim. In Ontario, a single lost-time injury in a warehouse environment averages $45,000–$85,000 in WSIB claim costs. Severe injuries (crush injuries, falls from height) can exceed $500,000.

This is not a theoretical risk. It is a recurring problem.

How Workers' Compensation Works With Temporary Staffing

Ontario (WSIB)

The Workplace Safety and Insurance Act, 1997, establishes that the "employer" is the entity that pays the worker's wages and controls the employment relationship. For temporary staffing, the staffing agency is the employer of record and must carry WSIB coverage.

However, WSIB Policy 12-01-05 specifically addresses temporary staffing and establishes dual responsibility:

• The agency is responsible for: WSIB registration, premium payment, reporting obligations, and return-to-work obligations.
• The client is responsible for: workplace safety, hazard identification, providing a safe work environment, and ensuring the agency worker receives the same safety training and protection as permanent employees.

If the agency's WSIB coverage lapses and a worker is injured at your site, WSIB will pursue the client company for claim costs under the "deemed employer" provisions. The rationale is straightforward: someone must pay, and you controlled the workplace where the injury occurred.

Quebec (CNESST)

The Act Respecting Industrial Accidents and Occupational Diseases operates on similar principles but with some key differences:

• In Quebec, the "establishment" where the worker performs duties can be held jointly responsible for claims if the staffing agency's CNESST registration is not current.
• Quebec has a more aggressive joint liability framework — the CNESST can and does pursue client companies when agencies default on premiums.
• Quebec also requires that temporary workers receive workplace-specific health and safety training before starting work, and the client is responsible for providing it.

Other Provinces

British Columbia (WorkSafeBC), Alberta (WCB Alberta), Manitoba (WCB Manitoba), and other provinces follow similar frameworks with provincial variations. The common principle is: the staffing agency carries the coverage, but the client facility shares responsibility for workplace safety and may become liable if the agency's coverage is deficient.

The Verification Protocol

Before You Sign a Staffing Contract

Request and verify the following from any staffing agency before they place workers at your facility:

1. WSIB/CNESST Account Number

Get the actual account number. Do not accept "we have coverage" as an answer. Then verify it independently:

• Ontario: Call WSIB at 1-800-387-0750 or use the online employer clearance certificate system. You can verify whether the account is active and in good standing.
• Quebec: Request a CNESST attestation of compliance (attestation de conformité). This document confirms the employer is registered and current on premiums.
• BC: Request a WorkSafeBC clearance letter.

2. Clearance Certificate

A WSIB clearance certificate confirms the employer has no outstanding balances and their account is active. In Ontario, you can request that the staffing agency provide a clearance certificate or you can look it up online using their legal business name and WSIB account number.

This is not a one-time check. Clearance certificates have expiration dates (typically 90 days in Ontario). Request updated certificates quarterly.

3. Rate Group Verification

WSIB premiums are based on rate groups. Staffing agencies that place workers in warehouses should be classified under rate group 849 (Employment Services) with a premium rate that reflects the risk profile of the client workplaces.

Some agencies attempt to reduce premiums by classifying their operations under lower-risk rate groups. If WSIB discovers this during an audit, the agency is reassessed — and while the reassessment is being processed, their coverage status may become uncertain. Verify the agency's rate group classification matches the type of work their employees perform at your site.

4. Insurance Certificate

In addition to WSIB/CNESST, request:

• Commercial general liability insurance ($2M minimum, $5M recommended)
• Certificate naming your company as additional insured
• Confirmation the policy includes coverage for temporary workers placed at client sites

What Happens When Coverage Lapses

Here is a real scenario we have encountered multiple times:

A staffing agency falls behind on WSIB premiums. WSIB issues a notice. The agency does not respond within the cure period. Coverage is suspended. The agency continues placing workers at client sites during the suspension period because stopping placements means stopping revenue.

A worker at Client X's warehouse is injured during the coverage lapse. The worker files a WSIB claim. WSIB discovers the agency's account was suspended. WSIB processes the claim (the worker is always covered regardless — this is a fundamental principle of the system) and then pursues the client company as the "deemed employer" for the cost of the claim plus administrative penalties.

Client X's WSIB account now carries a lost-time injury that was not their employee, increasing their own experience rating and future premiums. The total cost: the claim itself ($60,000), increased premiums over 3 years ($15,000–$30,000), and legal fees to dispute the deemed-employer assessment ($8,000–$20,000).

This entire scenario is prevented by quarterly verification of the agency's clearance certificate.

Your Contractual Protections

Your staffing agreement should include:

• Warranty of coverage: The agency warrants that it maintains active WSIB/CNESST coverage for all workers placed at your site, at all times.
• Indemnification: The agency indemnifies you for any costs arising from a lapse in their workers' compensation coverage.
• Notification obligation: The agency must notify you immediately if their coverage status changes for any reason.
• Right to verify: You have the right to verify the agency's coverage status at any time, and the agency will cooperate with verification requests within 48 hours.
• Termination trigger: A lapse in coverage constitutes grounds for immediate termination of the staffing agreement.

These contractual provisions do not replace verification — an indemnification clause is worthless if the agency goes bankrupt after a coverage lapse. But they establish the legal framework for recovery if a problem occurs.

The Daily Safety Obligation

Regardless of who carries the WSIB/CNESST coverage, you are responsible for providing a safe workplace. This means temporary workers must receive:

• Site-specific safety orientation before starting work
• Hazard-specific training for their assigned tasks
• The same PPE and safety equipment as permanent workers
• Inclusion in your joint health and safety committee processes
• The right to refuse unsafe work without reprisal

Treating temporary workers as second-class citizens in your safety program is not only ethically wrong — it increases your liability exposure. A WSIB investigation into a temporary worker injury will examine whether the worker received adequate training and safety orientation. If they did not, the "constructive direction" provisions can assign additional liability to your account regardless of the agency's coverage status.