Ontario law and employer duties

WSIB chronic mental stress claims: what Ontario employers should know

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Since January 1, 2018, Ontario workers can receive WSIB benefits for chronic mental stress, not only for sudden traumatic events. The WSIB chronic mental stress test is demanding, and it excludes ordinary employment decisions, but workplace harassment is generally treated as a substantial work-related stressor. This article explains what the policies say and what employers can do to prevent the harm behind the claims. For the rest of what Ontario law expects, see our guide to Ontario employers’ legal duties on workplace mental health.

What changed in 2018

Subsection 13(4) of the Workplace Safety and Insurance Act, 1997 now says a worker is entitled to benefits “for chronic or traumatic mental stress arising out of and in the course of the worker’s employment.” Subsection 13(5) sets the main exception, which we cover below.

The WSIB applies this through two operational policies:

Both current versions apply to all decisions made on or after March 1, 2024, for accidents on or after January 1, 2018. A separate policy (15-03-13) covers posttraumatic stress disorder in first responders and other designated workers, explained in our guide to WSIB traumatic mental stress and the PTSD presumption.

There was also a transition rule. If a worker’s chronic mental stress occurred on or after April 29, 2014, and no claim had been filed before January 1, 2018, the worker could file a claim on or before July 1, 2018.

The WSIB chronic mental stress test

Under policy 15-03-14, a worker will generally be entitled to benefits if “an appropriately diagnosed mental stress injury is caused by a substantial work-related stressor arising out of and in the course of the worker’s employment.” That sentence has three parts.

1. A diagnosis

Before a claim can be adjudicated, there must be a diagnosis under the Diagnostic and Statistical Manual of Mental Disorders (DSM). The policy names examples such as acute stress disorder, posttraumatic stress disorder, adjustment disorder, and anxiety or depressive disorders. The diagnosis can come from a physician, nurse practitioner, psychologist or psychiatrist. In complex cases, for example where a non-work stressor may have contributed, the WSIB may ask for a further assessment.

2. A substantial work-related stressor

A stressor is generally substantial if it is “excessive in intensity and/or duration in comparison to the normal pressures and tensions experienced by workers in similar circumstances.” The term includes multiple stressors and a cumulative series of stressors, so a long build-up can count, not just one event.

Jobs with a high degree of routine stress get specific treatment. A claim should not be denied simply because everyone in that occupation is exposed to high stress. The policy describes these jobs as involving responsibility for life-and-death matters or routine work in extremely dangerous circumstances.

3. The predominant cause

The decision-maker must be satisfied, on a balance of probabilities, that the stressor arose out of and in the course of employment and was the “predominant cause” of the injury. The policy defines this as the primary or main cause compared with each of the other individual stressors. A work stressor can still be the predominant cause even if all the other stressors combined outweigh it.

Evidence and witnesses

The WSIB must be satisfied that the events more likely than not occurred. The March 2024 revision made clear that a worker’s account does not need to be corroborated by witnesses. The absence of witness evidence “does not automatically result in the denial of entitlement,” although it may be relevant where such evidence would reasonably be expected.

How traumatic mental stress differs

Traumatic mental stress (policy 15-03-02) covers injuries caused by one or more traumatic events. The events must be clearly and precisely identifiable and objectively traumatic. Examples in the policy include witnessing a fatality or horrific accident, being the object of physical violence or death threats, and harassment that includes physical violence or threats of it.

The causation test is different. For traumatic mental stress, the event must have “caused, or significantly contributed to” the diagnosed injury. The policy also recognizes a cumulative effect: a reaction to the most recent event in a series can be accepted even if the worker coped with earlier ones.

Harassment as a stressor

Both policies define workplace harassment as “a course of vexatious comment or conduct against a worker, including bullying, that is known or ought reasonably to be known to be unwelcome,” by a person acting in the course of employment. Policy 15-03-14 states that workplace harassment “will generally be considered a substantial work-related stressor.”

Ordinary friction is treated differently. Conflicts with supervisors, co-workers or customers are “generally considered to be a typical feature of normal employment.” They are not usually a substantial stressor unless the conflict amounts to harassment or results in conduct a reasonable person would see as egregious or abusive.

The WSIB’s mental stress claims page gives examples of the behaviour it has in mind: intimidation, malicious rumours, gossip or innuendo, social isolation, coercion, humiliation, persistent insults, slurs and derogatory names, and physical abuse or threats of it.

Addressing harassment is also a duty under the Occupational Health and Safety Act. Employers must have a harassment policy (in writing and posted if more than five workers are regularly employed), a written program developed in consultation with the joint health and safety committee or representative, an investigation that is appropriate in the circumstances, and an annual review of the program (sections 32.0.1, 32.0.6 and 32.0.7). Our guide to Ontario harassment policy and program requirements covers these duties in more detail.

The employer’s decisions exception

Subsection 13(5) of the Act says a worker is not entitled to benefits for mental stress caused by the employer’s decisions or actions relating to the worker’s employment, “including a decision to change the work to be performed or the working conditions, to discipline the worker or to terminate the employment.”

Both policies list decisions that are part of the employment function:

  • terminations
  • demotions
  • transfers
  • discipline
  • changes in working hours
  • changes in productivity expectations

Decisions about workload and pace can fall here too. The WSIB’s own example of a business-related decision includes advising a worker to increase the pace of work to meet performance expectations for productivity, behaviour or service.

The exception has limits. Workers may be entitled where the employer’s decisions or actions are not part of the employment function, such as workplace harassment or conduct a reasonable person would see as egregious or abusive. For traumatic mental stress, the policy names violence or threats of violence. In short, the exception covers decisions that are part of the employment function. It does not extend to harassment or abusive conduct.

What the WSIB data shows

We could not find a year-by-year count of accepted chronic mental stress claims on the WSIB pages we were able to open, so we do not quote one here. The WSIB’s 2026 premium rate explanations do show where mental stress is affecting costs. For the Public Administration and Hospitals classes, the largest increase in claim costs was related to mental stress claims, including post-traumatic stress claims. The same was true for Metal, Transportation Equipment and Furniture Manufacturing. Mental stress claim costs also increased in the class that covers air and ground passenger transportation, courier services and warehousing. In other classes, such as Educational Services, they decreased.

Reporting a mental stress injury

The usual reporting rules apply. An employer must report a work-related accident if it learns that a worker needs health care, or is absent from regular work, earns less than regular pay, or needs modified work at less than regular pay or for more than seven calendar days. The WSIB must receive the employer’s complete report within three business days after the employer learns of the reporting obligation. Report the facts. Whether the claim is accepted is the WSIB’s decision.

Practical prevention steps for employers

The best way to manage chronic mental stress claims is to reduce the stressors that cause the injuries in the first place. These steps follow the shape of the policy.

  1. Treat harassment as a hazard. Keep your harassment policy and program current, make reporting routes clear (including one that bypasses the supervisor), investigate promptly and tell both parties the results in writing.
  2. Act on conflict early. Ordinary conflict is not a substantial stressor, but conflict left to escalate can become harassment. Supervisors need the skills to step in before it gets there.
  3. Deliver decisions with care. Discipline, transfers, schedule changes and new productivity targets fall within the employment function. Deliver them privately and respectfully, explain the reasons, and keep records.
  4. Watch intensity and duration. The test looks at stress that is excessive in intensity or duration. Track sustained overtime, staffing gaps and long periods of high demand, and fix them before they become the norm.
  5. Plan for critical events. If your work exposes people to violence, serious injuries or deaths, have a response plan, a debrief process and clear information about supports.
  6. Train people to notice and connect. A supervisor who can open a calm, private conversation and point someone to support can change how a hard stretch turns out. In a crisis, call or text 9-8-8, or call 9-1-1 if someone is in immediate danger.
  7. Measure and review. Use the 13 workplace factors in CSA Z1003 to find psychosocial hazards, keep a de-identified hazard register, and review it with your joint health and safety committee.

Where Bedrock Minds fits

Bedrock Minds is a blended psychological health and safety course published by Life Safe. It builds the skills behind the prevention steps above. It does not decide claims. The course is voluntary and is not a substitute for the instruction the OHSA requires.

  • The Responder stream is for all staff: about 5.5 hours online, covering the 13 workplace factors, the 4C Pathway (Check, Connect, Care, Close the loop) and critical events, followed by an in-person practical day.
  • The Champion stream is for supervisors, HR, JHSC members and program leads: about 10.5 hours online, including finding hazards, building the plan and measuring results. Learners finish with a written 90-day plan for their own organization.

If you also have federally regulated operations, read our guide to federal harassment and violence prevention training.

Give your people a plan they have practised

Bedrock Minds combines online modules with one practical day where staff and leaders rehearse the conversations this article describes. Tell us about your team and we reply within one business day.

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This article is general information, not legal advice.

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