Understanding what an HSE investigation involves helps employers prepare for regulatory enquiries and make informed decisions after an incident at work. As well as knowing what inspectors can require, employers need a clear approach to reporting, preserving evidence and examining what happened.
In this guide we explain employers’ reporting responsibilities and inspectors’ powers, along with practical steps to put investigation findings into practice to prevent future harm.
What is the HSE definition of an accident?
The HSE (Health and Safety Executive) defines an accident as “an event that results in injury or ill health” in Investigating accidents and incidents (HSG245).
This differs from a near miss, where no harm occurs but the event could have caused injury or ill health.
Both accidents and incidents provide opportunities to identify causes and prevent future harm.
How does an HSE investigation differ from an internal investigation?
An HSE investigation establishes what happened, whether health and safety law was breached and considers enforcement action. An internal employer investigation identifies the causes and changes needed to prevent a recurrence.
| Feature | HSE investigation | Internal employer investigation |
| Purpose | Assess legal compliance. Establish whether failures to manage risks breached health and safety law. | Establish why the event occurred and what needs to change to prevent a recurrence. |
| Trigger | A work-related incident or concern selected for investigation. | An accident, near miss or other event requiring examination. Events without injury can still reveal weaknesses in safety arrangements. |
| Investigators | HSE inspectors, sometimes with other authorities. Police and specialist regulators may be involved depending on what has happened. | Managers, safety advisers or an investigation team. Those involved should have the knowledge and experience to examine the event effectively. |
| Outcomes | Advice, improvement or prohibition notices, or prosecution. The response depends on the findings and seriousness of any breach. | Changes to equipment, risk assessments, procedures, supervision or training. Actions should have clear owners and deadlines, with checks to confirm they are effective. |
Is the HSE always responsible for health and safety investigations?
The HSE and local authorities share enforcement responsibilities in Great Britain. The relevant authority depends on the main activity carried out at the premises.
The HSE usually covers construction, manufacturing and agriculture, while local authorities cover offices, shops, hotels, restaurants and warehouses.
Some activities fall under specialist regulators, such as the Office of Rail and Road. See the HSE’s guidance on enforcement responsibilities.
What powers does an HSE inspector have?
HSE inspectors have statutory powers to enter premises, examine evidence, obtain relevant information and require assistance when enforcing health and safety law.
Under the Health and Safety at Work etc. Act 1974, Section 20, these powers include:
- Enter premises to carry out an inspection or investigation. They can enter at a reasonable time, or at any time if they believe the situation is or may be dangerous.
- Inspect equipment and how work is carried out. They can investigate what caused an incident and whether safety precautions were adequate.
- Collect evidence. They can take photographs, measurements and recordings, and collect samples of materials or air to check for hazards such as dust, fumes or gases.
- Require documents and take copies. These may include risk assessments, maintenance logs and training records. Documents protected by legal professional privilege, such as certain confidential communications with a solicitor, are exempt from compulsory disclosure.
- Require an area or item to be left untouched. This enables inspectors to examine the scene and preserve evidence for as long as reasonably necessary.
- Arrange for potentially dangerous equipment to be taken apart or tested, and substances to be tested. They must avoid damage or destruction unless necessary for the investigation.
- Take and retain potentially dangerous equipment or substances. This enables them to examine the items, prevent tampering or keep them as evidence for legal proceedings.
- Require people with relevant information to answer questions and confirm in writing that their answers are true. The person being questioned can choose someone to be present.
- Require practical help with the investigation. For example, they can require someone responsible for equipment to provide access or help arrange its examination.
- Bring authorised specialists and equipment to assist them. They can also bring a police officer if they have reasonable grounds to expect serious obstruction.
HSE inspectors can require people to answer questions under Section 20 to help establish what happened. These answers can help inspectors identify hazards, find witnesses and locate relevant records.
Inspectors can also interview someone under caution if they suspect that person has committed an offence. The person does not have to answer questions, and anything they say may be used as evidence. In England and Wales, failing to mention something they later rely on in court could harm their defence. Anyone invited to an interview under caution should seek legal advice beforehand.
Must every workplace accident be reported to HSE?
Not every workplace accident must be reported to HSE. The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR) set out which incidents must be reported to the relevant enforcing authority, usually HSE or the local authority. Employers should still record and investigate incidents through their internal procedures, however.
HSE’s reportable categories include work-related deaths, specified injuries, injuries that prevent a worker from doing their normal duties for more than seven consecutive days, certain diagnosed occupational diseases and specified dangerous occurrences. Some dangerous occurrences must be reported even when nobody is injured.
An accident is reportable only when it is work-related and meets the relevant reporting criteria. As HSE’s guidance explains, an accident happening on work premises is not automatically work-related. The work activity, equipment used or condition of the workplace must have contributed to it.
What are the RIDDOR reporting deadlines?
HSE’s reporting guidance sets out the following deadlines:
- Deaths, specified injuries to workers, reportable injuries to non-workers and dangerous occurrences: notify the enforcing authority without delay and ensure the completed report is received within ten days of the incident.
- Injuries preventing a worker from carrying out their normal duties for more than seven consecutive days: submit the report within 15 days of the accident. Exclude the day of the accident when calculating the period of incapacity but include weekends and rest days.
- Reportable occupational diseases: report as soon as the responsible person receives the diagnosis.
A worker may be unable to carry out their normal duties even if they still attend work. Do not wait for the internal investigation to finish before submitting a required report.
What happens during a fatal accident investigation?
A fatal accident investigation establishes how a work-related death happened and whether any criminal offences were committed.
The HSE and police work together from the start. The police investigate suspected manslaughter or homicide, while the HSE or another appropriate regulator examines possible breaches of health and safety law.
Work-related Deaths Protocols set out how the authorities coordinate their investigations. Separate arrangements apply in England and Wales, and in Scotland.
Employers must preserve evidence, follow the authorities’ instructions and coordinate any internal investigation with them. Specialist legal advice should be sought and support provided for affected colleagues and witnesses.
How can employers put investigation findings into practice?
Employers should turn investigation findings into an action plan that states what needs to change, who is responsible and when each action must be completed.
Address the causes identified
Choose actions that resolve the failures found during the investigation. If a leaking machine caused someone to slip, repair the leak and establish why it was not dealt with sooner. This may also require changes to fault reporting or maintenance arrangements.
Prioritise urgent risks and put temporary precautions in place until permanent repairs or improvements are complete.
Update risk assessments and procedures
Revise the relevant risk assessment to reflect what the investigation revealed and record the new precautions. Update working procedures so they explain how the task should now be carried out.
For example, if equipment must be isolated before clearing a blockage, the procedure should explain who can do this and the steps they must follow.
Check other equipment and sites
Look for the same problem elsewhere in the organisation. If a machine guard failed, inspect similar machines and check their maintenance records.
Ask site managers to confirm what they checked, what they found and any action required. Add further problems to the action plan so they are followed through.
Explain the changes to employees and contractors
Tell everyone affected what has changed and what they need to do. Use a demonstration or practical briefing where written instructions alone would be insufficient.
Ask employees to explain or demonstrate the revised procedure to check their understanding. Update induction information where new starters or contractors need the same instructions.
Check that actions are complete and effective
Draw on inspections, records and observations to confirm that repairs have been carried out correctly and employees can follow revised procedures during normal work. Resolve any problems before signing off the action.
For example, after installing barriers between pedestrians and vehicles, check that people use the designated routes and that deliveries do not create unsafe crossing points.
Assign someone to review the changes after an agreed period. Speak to employees and check for faults or near misses that could indicate further improvements are needed. Record the findings and any additional actions.
Strengthen your approach to accident prevention
After an incident at work, your organisation needs to establish what caused it, whether precautions were effective and what must change. Whether or not HSE investigates, a thorough internal investigation helps you answer these questions and prevent a recurrence.
Our Incident and Accident Investigation Training provides participants with the skills to gather and analyse evidence, identify root causes and recommend effective corrective actions.
Developed by health and safety experts, the course is available as online eLearning through our platform or your LMS via SCORM, or as face-to-face or virtual classroom training.
Find out more about Incident and Accident Investigation Training on our website, or contact our friendly team today on 0203 011 4242 / [email protected]
Adam Clarke
Managing Director (Consulting)
