Ontario OHSA for Office Employers: 16 Duties, Sorted by Headcount

Under Ontario's Occupational Health and Safety Act, a corporation convicted of an offence can be fined up to $2,000,000, and directors and officers up to $1,500,000 and/or 12 months in prison (Government of Ontario). Those penalties apply to a ten-person Toronto sales office just as they do to a factory.

Ontario is where many UK and international groups open their first Canadian office. Toronto is a hub for banking, insurance, law, technology and AI, and the first hires are often a sales team, a client services lead or a small engineering group. Health and safety is rarely on the launch checklist.

The Occupational Health and Safety Act (OHSA) is unusual in one helpful way: many of its duties switch on at specific headcounts. That makes it possible to plan. This guide sorts 16 duties into a headcount ladder, from the first worker to 50 and beyond, so you can see what applies now and what is coming as the team grows.

The thresholds below are based on workers "regularly employed" at the workplace. When you are close to a threshold, plan for the next rung rather than the current one.

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Rung 1: From Your First Worker

These duties apply to every Ontario employer covered by the Act, whatever its size.

Duty 1: Post the Act and the Ministry Poster

Employers must post a copy of the OHSA and the Ministry's explanatory material, including the Health & Safety at Work: Prevention Starts Here poster, in English and the majority language of the workplace. Since Bill 190 (the Working for Workers Five Act, 2024), this can be done in a readily accessible electronic format, provided workers know where to find it.

Duty 2: Complete Mandatory Awareness Training

Under Ontario Regulation 297/13, workers must complete basic health and safety awareness training, and supervisors must complete supervisor awareness training (often known as Supervisor Health and Safety Awareness in 5 Steps). Keep records. New managers in fast-growing offices are the most common gap.

Duty 3: Appoint Competent Supervisors

Anyone appointed as a supervisor must be competent, meaning they have the knowledge, training and experience to organise the work, know the Act and regulations that apply, and know about potential or actual dangers in the workplace. In a start-up office, the country manager is usually the first supervisor.

Duty 4: Take Every Reasonable Precaution

The general duty in clause 25(2)(h) requires employers to take every precaution reasonable in the circumstances for the protection of workers. For offices, that means assessing everyday risks such as workstations, slips and trips, fire safety and workload. Our office risk assessment guide shows the method.

Duty 5: Have Workplace Violence and Harassment Policies

Every employer must have policies on workplace violence and workplace harassment, and review them at least once a year. Since Bill 190, the definitions of workplace harassment and workplace sexual harassment expressly include virtual harassment through email, chat, video calls and other technology. See the Ministry's guide to Part III.0.1.

Duty 6: Run Programs to Implement Them

Policies need programs behind them: how incidents are reported, how they are investigated, how information is kept confidential, and how complainants and alleged harassers are told the outcome. Programs must be reviewed as often as necessary, and at least annually for harassment.

Duty 7: Assess the Risk of Workplace Violence

Employers must assess the risks of workplace violence that may arise from the nature of the workplace, the type of work or the conditions of work, and reassess as often as necessary. Client-facing offices, reception areas and late working all deserve attention. Employers who are aware, or ought reasonably to be aware, that domestic violence may occur in the workplace must also take reasonable precautions.

Duty 8: Know Your Reporting Duties

Fatalities and critical injuries must be reported immediately to the Ministry, and other reporting duties apply to lost-time injuries and occupational illnesses. Make sure your local manager, not just head office, knows who to call. See when the clock starts: 12 reporting deadlines across jurisdictions.

Duty 9: Arrange First Aid

Ontario's first aid requirements sit under the workplace insurance system rather than the OHSA, and scale with the number of workers per shift. They cover first aid kits, trained first aiders and posted information. See the WSIB first aid guidance, and our first aid overview.

Duty 10: Cover Remote and Hybrid Workers

Many Ontario office teams work partly from home. Bill 190 addressed how the Act applies to telework, and its harassment changes already apply to virtual conduct wherever it happens. Your home working assessments, violence and harassment policies and reporting routes should all reflect remote work. See work-from-anywhere policies: 5 questions they miss.

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Rung 2: Six or More Workers

Duty 11: Write, Post and Review a Health and Safety Policy

Where more than five workers are regularly employed, the employer must prepare a written occupational health and safety policy, review it at least once a year, set up a program to implement it, and post it where workers will see it or in a readily accessible electronic format. See our guide to what a health and safety policy must contain.

Duty 12: Put Violence and Harassment Policies in Writing and Post Them

At six or more regularly employed workers, the violence and harassment policies from Duty 5 must also be in writing and posted, physically or electronically.

Duty 13: Support a Health and Safety Representative

Where the number of workers regularly exceeds five and no joint committee is required, workers select a health and safety representative from among those who do not exercise managerial functions. The employer must cooperate, share relevant information, and allow time for the role.

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Rung 3: Twenty or More Workers

Duty 14: Establish a Joint Health and Safety Committee

At 20 or more regularly employed workers, a joint health and safety committee (JHSC) replaces the representative. At least half the members must be workers who do not exercise managerial functions. A worker member must inspect the workplace, usually monthly, or on a schedule that covers the whole workplace at least once a year. The committee meets at least every three months, and since Bill 190 meetings can be held virtually. The employer must respond in writing to committee recommendations. See the Ministry's guide to Part II.

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Rung 4: Twenty-Five or More Employees

Duty 15: Add the Related Employment Standards Policies

This one sits under Ontario's Employment Standards Act rather than the OHSA, but it lands on the same desk. Employers with 25 or more employees on 1 January of a year must have written policies on disconnecting from work and on electronic monitoring. The disconnecting policy is closely linked to workload and stress, so it belongs alongside your health and safety arrangements.

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Rung 5: Fifty or More Workers

Duty 16: Have Certified JHSC Members

At workplaces with 50 or more regularly employed workers, the JHSC must include certified members: at least one representing workers and at least one representing the employer. Certification involves specific training approved under the Act, and takes time to arrange. Book it before you reach 50, not after.

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The Ladder at a Glance

Workers regularly employed	Duties that switch on
1 or more	Posting, awareness training, competent supervisors, general duty, violence and harassment policies and programs, violence risk assessment, reporting, first aid, remote work
6 or more	Written and posted health and safety policy, written and posted violence and harassment policies, health and safety representative
20 or more	Joint health and safety committee
25 or more employees	Disconnecting from work and electronic monitoring policies (Employment Standards Act)
50 or more	Certified JHSC members

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How Ontario Compares With a UK Head Office

UK groups often assume Ontario will look like home. Several things differ:

Topic	United Kingdom	Ontario
Written health and safety policy	Required at five or more employees	Required where more than five workers are regularly employed, reviewed annually
Worker representation	Consultation duties; safety representatives where unions are recognised	Health and safety representative at 6 to 19 workers, JHSC at 20 or more
Harassment	Equality law, plus a preventative duty on sexual harassment since 2024	Specific OHSA policies and programs for violence and harassment, including virtual harassment
Mandatory awareness training	No single prescribed course	Prescribed worker and supervisor awareness training
Maximum corporate fine	Unlimited, guided by turnover	Up to $2,000,000 per offence

The structure in Ontario is more prescriptive, which makes it easier to check, and easier to fall short of if nobody is watching.

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Sector Notes

Banking, insurance and legal: client-facing teams, high workloads and late working make Duties 5 to 7 and Duty 15 especially relevant. See our finance health and safety in Canada article, and our insurance and legal pages.

Software and AI: fast hiring pushes offices through the 6, 20 and 50 thresholds quickly, often within a year. Track headcount against the ladder. See our software and AI and data pages.

Education: colleges, universities and international schools with Ontario campuses have students and visitors as well as staff, and larger, more complex sites. See our education page.

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How Arinite Helps

Arinite has supported 1,500+ businesses across 50+ countries for 15+ years, protecting 100,000+ employees, with 95%+ client retention. Our qualified consultants help UK and international groups set up and maintain Ontario arrangements as part of one consistent system. See our Canada page and our guide to health and safety consultants in Hamilton, Ontario.

• Done For You: our health and safety consultants prepare your Ontario policies, programs and risk assessments, and check them through annual health and safety audits.
• Done With You: we help you set up your representative or JHSC, plan certification ahead of the 50-worker threshold, and train local managers.
• DIY: you hold policies, training records, JHSC minutes and actions on our health and safety consultants and software platform, with reminders for every annual review.

As international health and safety consultants, we align Ontario requirements with your UK and other overseas arrangements, and our global health and safety consultants keep every office on one group standard.

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Frequently Asked Questions

Does Ontario's OHSA apply to office workplaces?

Yes. The Act applies to most workplaces in Ontario, including offices. Many duties, such as violence and harassment policies, awareness training and the general duty to take every reasonable precaution, apply from the first worker.

When does an Ontario employer need a JHSC?

A joint health and safety committee is generally required where 20 or more workers are regularly employed. Between six and 19 workers, a health and safety representative is required instead.

Do workplace harassment policies in Ontario cover remote work?

Yes. Since the Working for Workers Five Act, 2024, the definitions of workplace harassment and workplace sexual harassment expressly include virtual harassment through information and communications technology.

Can Ontario OHSA documents be posted electronically?

Yes. Employers can meet posting requirements with a readily accessible electronic format, provided workers are told where and how to access it.

What training is mandatory for supervisors in Ontario?

Supervisors must complete health and safety awareness training that meets Ontario Regulation 297/13, commonly delivered as Supervisor Health and Safety Awareness in 5 Steps, in addition to any workplace-specific training.

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Know Which Rung You Are On

Check your Ontario headcount today, then check which duties on the ladder you have actually put in place. Book a free gap analysis with Arinite and we will review your Ontario arrangements alongside your UK and international ones, and show you what to fix before your next hire.

Request your free gap analysis