Workplace Incident Notice and Reporting Regulation (O. Reg. 420/21)

Ontario’s Occupational Health and Safety Act (OHSA) sets out, in sections 51 to 53.1, who an employer must notify when a worker is killed, critically injured, otherwise hurt, or develops an occupational illness — and how fast. The regulation on this page, O. Reg. 420/21 (Notices and Reports under Sections 51 to 53.1 of the Act), supplies the detailed mechanics behind that Act-level duty: the precise definition of a “critical injury,” exactly what each written report or notice must contain, when an engineer’s written opinion is also required, how long records must be kept, and how to file electronically. The Act says who and how fast; this regulation says what goes in the report and what you keep.

This page explains those mechanics in plain language and links each rule to the official source. The duties here are procedural — they govern the content and handling of the filings, not whether an incident is reportable in the first place. That threshold question lives in the Act itself; see the reporting section of the OHSA page for who must be told and within what window.

What "critically injured" means, and where these reporting rules apply (the highway-collision carve-out)

A “critical injury” is not left to judgment. It is an injury of a serious nature that does any one of these: places life in jeopardy; produces unconsciousness; results in substantial loss of blood; involves the fracture of a leg or arm (but not a finger or toe); involves the amputation of a leg, arm, hand or foot (but not a finger or toe); consists of burns to a major portion of the body; or causes the loss of sight in an eye.

If any of those has happened, the injury is critical. The test is the list, not an employer’s instinct: a common error is downplaying an injury that ticks one of the boxes above. “Medical attention” likewise has a set meaning — treatment from a legally qualified medical practitioner, or a registered nurse holding an extended certificate of registration. First aid administered by a coworker is not “medical attention.”

The regulation applies to every workplace the Act covers. The one notable exception is the specific reporting duty in section 3, which is switched off when a worker is killed, critically injured, disabled from their usual work, or needs medical attention because of a motor-vehicle collision on a public highway (or Highway 407). That carve-out itself has two exceptions, so the duty still applies if the worker was working at a construction project at the time, or was not actually riding in the vehicle when the crash happened. A second common error is the reverse: assuming a roadside crash is never reportable.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), ss. 1–2.

Confidence: single-source.

What must a written report for a workplace fatality or critical injury contain?

When a worker is killed or critically injured at a workplace from any cause, O. Reg. 420/21 requires a written report that includes the employer’s name, address and type of business, the injured worker’s name and home address, the nature of the bodily injury, the constructor’s name and address if the incident happened on a construction project, the nature and circumstances of what happened (including any machinery, equipment or procedure involved), the time, date and place, the name and address of the medical practitioner, registered nurse or medical facility that treated the worker, contact information for any witnesses, and the steps taken to prevent a recurrence.

This is the serious-incident report, separate from the lighter notice owed for an accident where a worker is hurt but not critically. The regulation spells out exactly what that report must contain. Setting the prescribed fields out item by item:

• The employer’s name, address and type of business, plus the injured worker’s name and address.
• The nature of the bodily injury.
• If the incident happened on a construction project, the constructor’s name and address.
• The nature and circumstances of what happened, including any machinery, equipment or procedure that was involved.
• The time, date and place.
• The name and address of the legally qualified medical practitioner, the registered nurse holding an extended certificate of registration, or the medical facility that treated or is treating the worker.
• Contact information for any witnesses.
• The steps taken to prevent a recurrence.

That last point is forward-looking: the report is not just a record of the past — it asks what the employer is doing going forward. A common error is treating the verbal call to the Ministry as the whole job. The phone call does not replace the written report, and a thin report that skips the witnesses or the prevention steps is an incomplete one; names and details are best gathered at the scene while they are fresh. A fatality or critical injury triggers other obligations too, so proper help is worth getting early.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), s. 3.

Confidence: single-source.

What goes in a death, injury or illness report (section 52)?

The law does not just require that a serious event be reported — it prescribes exactly what each report or notice must contain. O. Reg. 420/21 sets the required content for three distinct situations: a worker is killed or critically injured at a workplace, from any cause; a worker is hurt or made ill enough by an accident, explosion, fire, or act of workplace violence that they cannot do their usual job or need medical attention, but nobody died or was critically injured; or the employer is told — directly by the worker or on their behalf — that a worker has an occupational illness, or that a WSIB claim for one has been filed.

Every report or notice, regardless of which situation applies, must include the employer’s business name, address and type of business, the affected worker’s name, and the nature of the injury or illness. Every report or notice also requires witness contact information (names, addresses, or other contact details) and a description of the steps taken to prevent a recurrence or further illness. These universal fields apply across all three situations — including a death or critical-injury report.

Beyond those universal fields, each situation has its own additional requirements:

• Death or critical injury. The written report needs the worker’s home address, the constructor’s name and address if the incident happened on a construction project, a description of what happened and how (including any machinery, equipment or procedure involved), the time, date and location of the incident, and the name and address of the medical practitioner, registered nurse or medical facility that attended to the worker.
• Lesser injury or workplace violence (no death or critical injury). The notice requires a description of how the incident unfolded and what equipment or procedures were involved, along with the time, date and place.
• Occupational illness. The notice requires a description of the cause or suspected cause of the illness.

The items that catch employers off guard are that witness contact information and the prevention-steps field are required on every type of filing, not just the serious ones. A thin report on any incident invites follow-up from an inspector.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), s. 3.

Confidence: single-source.

Section 53 incident notices: construction, mine and mining-plant incidents and the required contents

Section 53 of OHSA covers the heavier-duty workplaces — construction projects, mines and mining plants — and requires a written notice when something serious happens. This regulation does two things: it lists which incidents trigger that notice, and it sets out what the written notice itself must contain.

What triggers a notice. The baseline triggers under the Act itself are an accident, a premature or unexpected explosion, fire, flood or inrush of water, a cave-in, subsidence or rockburst at one of those sites. Equipment failure that could have posed a risk to worker life, health or safety at those locations also counts. The regulation then adds a long list of prescribed incidents tied to sector-specific rules:

• Diving operations: a diver trapped underwater, a missed decompression requirement, a diving equipment failure posing a health or safety risk, an emergency rescue using a submersible compression chamber or atmospheric diving system, emergency use of a recompression chamber, anyone going unconscious, or decompression sickness.
• Construction: a worker falling three metres or more vertically, a fall arrested by a fall-arrest system (other than a fall-restricting system), a worker losing consciousness for any reason, accidental contact by a worker or their tool with energized electrical equipment or conductors, accidental contact by a crane or similar equipment or its load with an energized conductor rated above 750 volts, structural failure of engineered falsework, failure of a principal structural member such as a column, beam, wall or truss, collapse of scaffold structural supports, failure of an earth- or water-retaining structure including temporary shaft or trench supports, failure of an engineered excavation wall, overturning or structural failure of a crane or similar hoisting device, or loss of control of a crane or load.
• Mines and mining plants: a hoist, rope, shaft conveyance or shaft lining failure; flammable gas present in an underground workplace; spontaneous heating with gas evolution; major failure or damage to electrical equipment, railroad equipment, a crane or a motor vehicle underground; a rockburst that displaces more than five tonnes of material; an uncontrolled fall of ground displacing more than 50 tonnes; a defective fuse, detonator or explosive; a structural failure in anything requiring an engineer’s design under the mines regulation; or an unexpected and uncontrolled run of material, water or slimes exceeding one cubic metre that could have put a worker at risk.
• X-ray safety: a worker receiving, within any three-month period, a dose equivalent above the annual limits in the X-ray Safety regulation schedule; or an accident, equipment failure or other incident that may have resulted in a worker receiving a dose above the separate threshold limits in that same schedule.

What the notice must say. Plainly: the employer’s name, address and type of business; on a project, the constructor’s name and address; the time, date and place of the occurrence; the nature and circumstances, including any machinery, equipment or procedure involved; and the steps taken to prevent a recurrence.

A common error is assuming “no injury, no report.” Several of these triggers are near-misses — equipment failed or a structure gave way even if nobody got hurt — and the duty to give notice still applies. The precise duties and timing turn on which regulation governs the site, so confirm before relying on this.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), s. 4.

Confidence: single-source.

Additional notices: when a construction, health-care or window-cleaning incident also needs an engineer's written opinion (within 14 days)

For a narrow set of construction, health-care and window-cleaning incidents — generally a structural, excavation, crane or hoisting failure — the report or notice already owed under sections 51 to 53 must be backed up by a written opinion from an engineer explaining the cause of the incident, and the engineer’s written opinion must be delivered within 14 days of the occurrence.

When a serious incident happens, reporting duties already arise under the Act: a written report to a Director for a fatality or critical injury, and notices for certain other occurrences. This regulation adds a second step for a narrow set of incidents — alongside that initial report or notice, the employer must also obtain and provide a written engineering opinion on the cause. The obligation to get that opinion is triggered by the type of workplace and the nature of the failure:

• Construction projects (where Ontario Regulation 213/91 applies): the incident involves all or part of a structure, temporary or permanent works, an excavation wall whose stability an engineer had previously certified in writing, or a crane or similar hoisting device. It also applies when someone loses control of a crane or its load — rigging failures included — unless the loss of control falls within what section 162 of that regulation expressly permits.
• Health care and residential facilities (where Ontario Regulation 67/93 applies): a structure — temporary or permanent — designed by either an engineer or an architect has buckled or given way.
• Window cleaning workplaces (where Regulation 859 applies): a support or structure of any kind — temporary or permanent — that an engineer designed has buckled or given way.

The deadline is firm: the engineer’s written opinion must be delivered within 14 days of the occurrence. A common error is filing the initial report on time and assuming the job is done, not realizing one of these structural or hoisting failures pulls in the separate engineering-opinion requirement. The 14-day clock runs from the incident itself, not from when the employer decides to hire the engineer, so it pays to engage one right away. If a structural, crane or rigging failure is involved, confirm the reporting obligations with a qualified professional promptly.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), s. 5.

Confidence: single-source.

Keeping records and filing notices electronically (three-year retention; the Ontario online form)

When a serious workplace event triggers a written notice or report to the Ministry, the rule has two practical parts: keep the paperwork, and the filing can be done online.

Retention. Whether an employer or a constructor, the duty-holder must keep a copy of any written notice or report it gives about a fatality, critical injury, occupational illness or other reportable incident. The clock runs for at least three years from the date the notice or report was made. That is a floor, not a ceiling, so there is no harm in keeping it longer.

Electronic filing. Paper is not required. The regulation confirms that:

• A written report or notice to a Director can be filed by completing the form on the Government of Ontario website.
• The same applies to the copy owed to the joint health and safety committee, the health and safety representative, and the union (if there is one) — an electronic copy of that same online form satisfies that duty.

A common error is filing the government form but forgetting the internal copies, or treating the online submission as the end of it and discarding the record. The safe practice is to keep proof that it was sent and proof of what was sent, for the full three years. The record-keeping rule assumes the threshold question — whether a particular event is reportable in the first place — has already been resolved; if that is unclear, advice is worth getting before the deadline passes.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), ss. 6–7.

Confidence: single-source.

Commencement and administrative provisions

The closing sections of O. Reg. 420/21 are housekeeping, and they impose no separate duty on employers. They confirm the regulation is in effect and otherwise point back to the operative sections above.

The last two sections do the following:

• Knock-on changes to other rules. One section deals with how this regulation amends, repeals or revokes other pieces of legislation. In the official version it is marked “omitted,” because its only job was to tidy up the surrounding rulebook when the regulation came in.
• Coming into force. The other section sets the start date — when the regulation’s provisions began to apply. It too is shown as “omitted” in the consolidated text, since the date has already passed and the rules are live.

The error to avoid is reading too much into these tail-end sections, or skipping the parts that matter because the ending looks empty. The duties that bite — who must be notified, how fast, and what the report has to contain — all live in the earlier sections of the regulation. These closing provisions are a signpost: they confirm the regulation is in effect, then point back to the real reporting requirements above.

Source: Notices and Reports under Sections 51 to 53.1 of the Act (O. Reg. 420/21 under the Occupational Health and Safety Act, R.S.O. 1990, c. O.1), ss. 8–9.

Confidence: single-source.

General information, not legal advice

This page is general information about Ontario occupational health and safety law, not legal advice. A fatality, critical injury, occupational illness or other reportable incident triggers tight deadlines and obligations beyond the ones described here, and the precise duties and timing turn on which regulation governs the workplace. When working out whether and how a particular incident must be reported, check the operative sections of O. Reg. 420/21 and the Act-level reporting duty in OHSA sections 51 to 53.1, and obtain advice on the specific situation before acting.