When Are Employers Required to Conduct a Workplace Investigation?

I get asked this question a lot, usually by employers who’ve just received a complaint and are hoping the answer is “not always.”

Fair enough. Not every workplace gripe needs a formal investigation. But here’s the thing: more complaints require investigation than most employers think. And the consequences of deciding not to investigate when you should have can be far worse than the cost and disruption of the investigation itself.

So when is a workplace investigation actually required? Let’s cut through the noise.

The Legal Position: There’s No Single Rule

There’s no single piece of Australian legislation that says “you must investigate every complaint.” But there are multiple legal obligations that, taken together, create a very strong expectation that employers will investigate serious workplace complaints. These obligations come from several sources.

Work Health and Safety Laws

Under the Work Health and Safety Act, employers have a primary duty of care to ensure, so far as is reasonably practicable, the health and safety of workers. Recent regulatory amendments have made explicit what was always implicit – that psychological health is part of an employer’s WHS duty. If an employee reports bullying, harassment, or other conduct that creates a psychosocial risk, ignoring it isn’t just bad management – it’s a potential breach of your WHS obligations.

Employers now have a positive duty to identify and manage psychosocial hazards. A formal complaint is about as clear a signal as you’re going to get that a hazard may exist. Failing to investigate it is failing to manage the risk.

Anti-Discrimination and Equal Opportunity Laws

If a complaint involves sexual harassment, discrimination, or any conduct covered by the Sex Discrimination Act, the Racial Discrimination Act, the Disability Discrimination Act, or equivalent state legislation, employers have specific obligations. Under the positive duty provisions introduced in the Sex Discrimination Act, employers must take reasonable and proportionate measures to eliminate unlawful sex discrimination and sexual harassment. Investigating complaints is one of the most fundamental of those measures.

If a discrimination or harassment complaint goes uninvestigated and the matter ends up before the Australian Human Rights Commission or a state tribunal, the employer’s failure to investigate will be front and centre. It’s very difficult to argue you took reasonable steps to address the issue if you didn’t even look into it.

Fair Work Act Obligations

If an employer takes adverse action against an employee – termination, demotion, a formal warning – that action needs to be based on a sound and defensible process. If the adverse action relates to alleged misconduct, the Fair Work Commission will want to see that the allegations were properly investigated before any decision was made. An employer who terminates someone without investigating the underlying complaint is asking for an unfair dismissal claim.

The Fair Work Commission has been very clear on this: a valid reason for dismissal isn’t enough. The process has to be fair, and a fair process almost always includes an investigation.

Your Own Policies

Here’s one that catches a lot of employers out. If your workplace policies say complaints will be investigated, then they need to be investigated. It sounds obvious, but I regularly see organisations with beautifully written complaint-handling policies that promise thorough investigation and fair outcomes – and then do nothing when a complaint actually arrives.

Your policies create expectations. If an employee relies on those expectations and you don’t follow through, that’s a problem – both legally and in terms of workplace trust.

When a Workplace Investigation Is Clearly Required

While every situation is different, there are certain categories of complaints where an investigation is almost always necessary:

Allegations of bullying or harassment. Whether it’s a formal written complaint or a verbal report to a manager, allegations of workplace bullying or harassment need to be investigated. The severity of the allegations will determine the scope and formality of the investigation, but ignoring them is not an option.

Sexual harassment complaints. Always. No exceptions. Given the current regulatory environment and the positive duty obligations, failing to investigate a sexual harassment complaint is one of the highest-risk decisions an employer can make.

Discrimination complaints. If an employee alleges they’ve been treated unfavourably because of a protected attribute – race, gender, disability, age, sexuality, religion – that complaint requires investigation.

Serious misconduct allegations. Theft, fraud, safety breaches, violence, intoxication at work – these are matters where the potential consequences for the individual are significant (including termination), so the investigation needs to be thorough and procedurally fair.

Repeated or escalating complaints. If you’re getting multiple complaints about the same person or the same issue, that’s a pattern. Patterns need investigation, not just another informal chat.

Complaints that could result in adverse action. If the outcome of the complaint could lead to a warning, demotion, or termination, you need an investigation to support that decision. Taking adverse action without an investigation is the employment law equivalent of building a house without foundations.

See also: Who Should Conduct a Workplace Investigation?

When You Might Not Need a Formal Investigation

Not every workplace issue requires a formal, external investigation. Some situations can be resolved through other means:

Minor interpersonal conflicts. Two colleagues who aren’t getting along over workload distribution or communication styles may benefit more from a facilitated conversation or mediation than a formal investigation.

Performance issues. Poor performance is generally managed through performance management processes, not investigations – unless the performance issue is intertwined with allegations of misconduct.

Complaints where the facts are not in dispute. If everyone agrees on what happened and the only question is what to do about it, you may not need a formal fact-finding investigation. But tread carefully here – what looks straightforward on the surface can turn out to be more complex once you scratch beneath it.

A word of caution: even in these situations, document your decision-making. If you decide not to formally investigate a complaint, record why you made that decision and what alternative action you took. If the matter escalates later, you’ll want to show that you gave it proper consideration rather than just hoping it would go away.

The Cost of Not Investigating

Employers who choose not to investigate serious complaints are making a calculated bet that the problem will resolve itself. Spoiler: it almost never does. Here’s what actually happens.

The behaviour continues or escalates. If someone is bullying or harassing a colleague and nothing happens when a complaint is made, they’ve just learned there are no consequences. The behaviour gets worse.

The complainant loses trust and leaves – or goes external. When an employer ignores a complaint, the complainant has limited options. They either suffer in silence, resign (hello, constructive dismissal claim), or take the complaint to an external body like the Fair Work Commission, the Australian Human Rights Commission, or a WHS regulator. None of these outcomes are good for the employer.

Other employees notice. People talk. If word gets around that a serious complaint was ignored, it sends a clear message: this organisation doesn’t take complaints seriously. Expect your engagement scores to drop and your turnover to rise.

Psychosocial risks multiply. An uninvestigated complaint doesn’t just affect the complainant. It creates a psychologically unsafe environment for everyone who knows about it. Under current WHS laws, that’s a hazard you’re failing to manage.

Your legal position weakens dramatically. If the matter ends up in a tribunal or court, the first question will be: what did the employer do when the complaint was raised? “Nothing” is not an answer that goes well for anyone.

The Grey Area: Anonymous Complaints, Third-Party Reports, and Whistleblower Disclosures

What about complaints that come through anonymous channels, or reports from a third party who witnessed something but isn’t the direct target? These are trickier, but they don’t let you off the hook.

An anonymous complaint that contains specific, credible allegations still needs to be assessed and, in most cases, investigated. You may not be able to provide the same level of procedural fairness (because there’s no complainant to interview), but that doesn’t mean you ignore it. Similarly, if a manager witnesses conduct that could constitute bullying, harassment, or misconduct, they have a responsibility to report it and the organisation has a responsibility to act on it – regardless of whether the affected person has made a formal complaint.

And then there are whistleblower disclosures, which add another layer entirely. Under the Corporations Act, employers have specific obligations to protect whistleblowers who report misconduct, illegal activity, or conduct that represents a danger to the public. If a disclosure is made through a whistleblower channel – whether internal or external – the organisation must take it seriously, investigate appropriately, and critically, protect the identity of the whistleblower.

The penalties for failing to protect a whistleblower, or worse, retaliating against one, are severe. This isn’t an area where you want to wing it. If you receive a whistleblower disclosure, get specialist advice before you do anything else, because the way you handle the investigation from the outset matters enormously.

The principle across all of these situations is simple: once the organisation is on notice that there may be a problem, it needs to respond. The form of that response will depend on the circumstances, but “we didn’t get a formal written complaint” is not a defence for inaction.

The Bottom Line

When is a workplace investigation required? In short: whenever a serious complaint is raised and you need to understand what happened before you can decide what to do about it. The legal framework across WHS, anti-discrimination, and employment law all point in the same direction – employers are expected to take complaints seriously and respond proportionately.

If you’re sitting on a complaint right now and wondering whether you really need to investigate, ask yourself this: if this matter ended up before a tribunal or regulator next month, would you be comfortable explaining your decision not to investigate? If the answer is anything other than a confident yes, you know what you need to do.

Related reading: How to choose a workplace investigator (what to look for, red flags, and when to go external)

Unsure whether your situation requires a formal workplace investigation? Segal Conflict Solutions can help you assess your options and, if needed, conduct an independent workplace investigation. Get in touch for a confidential, obligation-free conversation.