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.

You’ve received a workplace complaint and you know it needs to be investigated. The next question is: who’s going to do it? Do you hand it to your HR team to manage internally, or do you bring in an external workplace investigator?

It’s not always an obvious call. Both options have their place. But in my experience, organisations get this decision wrong more often than they get it right – usually because they default to the cheaper or more convenient option without thinking through the consequences. And by the time they realise the investigation has a credibility problem, it’s too late to fix it.

Let’s break down when each approach works, when it doesn’t, and how to make the right call for your situation.

Internal Workplace Investigations: When They Work

An internal workplace investigation is conducted by someone within the organisation, usually a senior HR professional, an in-house lawyer, or sometimes a manager with appropriate training.

Internal investigations can work well when the complaint is relatively straightforward – a single allegation, limited witnesses, no involvement of senior leadership, and no pre-existing tensions that could compromise the process. If your HR team is trained in workplace investigations and has the time and capacity to manage the process properly, handling a low-level complaint internally can be efficient and cost-effective.

Advantages of Internal Investigations

Cost. The most obvious one. You’re using existing staff, so there’s no external fee. For straightforward matters, this can make good financial sense.

Organisational knowledge. An internal investigator already understands the culture, the policies, the reporting lines, and the context. They don’t need a briefing on how the organisation works.

Speed. In theory, an internal investigator can get started immediately without the procurement process of engaging an external provider.

The Problems with Internal Investigations

Here’s where it gets tricky. The advantages of internal investigations are also their weaknesses.

Perceived bias. This is the big one. No matter how fair and competent your HR team is, an internal investigator is employed by the same organisation as the complainant and the respondent. They report to the same leadership. They have ongoing working relationships with the people involved. For the person making the complaint, it’s entirely reasonable to wonder: can this person really be impartial when their boss is the one being complained about?

Capacity and competing priorities. Internal investigators rarely have the luxury of dropping everything to focus on an investigation. They’re still doing their day job, still answering emails, still getting pulled into meetings. Investigations get squeezed in between everything else, and timelines blow out. I’ve seen internal investigations take four months for matters that an external investigator would have wrapped up in four weeks.

The aftermath problem. Here’s something nobody talks about: the internal investigator still has to work with these people once the investigation is done. They have to sit in meetings with the person they didn’t substantiate allegations against. They have to manage the HR file of the person who was disciplined based on their findings. That’s an incredibly uncomfortable position, and it can – consciously or unconsciously – influence how they approach the investigation in the first place.

Training gaps. Being a good HR professional doesn’t automatically make someone a good investigator. Workplace investigations require specific skills in evidence gathering, interviewing, procedural fairness, and report writing. If your HR team hasn’t been formally trained in these areas, the investigation may not withstand scrutiny.

External Workplace Investigations: When to Bring Someone In

An external workplace investigation is conducted by an independent professional engaged specifically for the matter. This is typically a specialist workplace investigator, a lawyer with investigation experience, or someone with a background in both.

Advantages of External Investigations

Independence and credibility. An external investigator has no stake in the outcome and no ongoing relationship with the parties. This is the single most important factor in whether the people involved trust the process. And trust in the process is everything. If the complainant doesn’t believe the investigation was fair, you’ll end up dealing with a second complaint about the investigation itself.

Dedicated focus. An external investigator is engaged to do one thing: investigate this matter. They’re not juggling it alongside their regular workload. This typically means faster turnaround and a more thorough process.

Specialist expertise. Experienced external investigators do this all day, every day. They know how to manage complex interviews, navigate procedural fairness requirements, and write reports that stand up to legal challenge. They’ve seen the patterns and they know the pitfalls.

Related reading: Who Should Conduct a Workplace Investigation?

Risk management. If the matter ends up at the Fair Work Commission, in a workers’ compensation claim, or before a regulator, having an independent, external investigation significantly strengthens your position. It demonstrates that the organisation took the complaint seriously and managed the process with integrity.

The Downsides of External Investigations

Cost. Let’s be honest about it. External investigators charge fees, and for complex matters, those fees add up. But I’d argue the cost of a proper external investigation is almost always less than the cost of getting it wrong internally – in terms of legal exposure, staff turnover, workers’ compensation claims, and reputational damage.

Ramp-up time. An external investigator needs to be briefed on the organisation, its policies, and the context of the complaint. This takes time at the outset, though a good investigator will manage this efficiently and it rarely adds more than a day or two to the overall timeline.

How to Decide: A Practical Framework

Forget about cost for a moment. The question you should be asking is: will the people involved trust this process?

If the answer is yes – if the complaint is straightforward, the HR team is trained and credible, and there’s no conflict of interest or perception of bias – an internal investigation may be perfectly appropriate.

If there’s any doubt, go external. Specifically, consider an external workplace investigation when:

The complaint involves senior leadership or management. When the person being complained about has power within the organisation, an internal investigation will always struggle for credibility – even if it’s conducted perfectly.

There are multiple or complex allegations. Matters involving several allegations, multiple parties, or allegations spanning a long period need specialist skills and dedicated time that most internal teams can’t provide.

There’s potential legal exposure. If the matter could result in a Fair Work claim, an anti-discrimination complaint, a workers’ compensation claim, or regulatory action, you need an investigation that will withstand external scrutiny.

Trust in the organisation is already low. If employees are cynical about the organisation’s willingness to address complaints fairly, an internal investigation will confirm their worst assumptions. An external investigator sends a clear message that the organisation is taking the matter seriously.

The complaint involves systemic or cultural issues. If the complaint suggests problems that go beyond one individual – a culture of bullying, widespread harassment, or systemic unfairness – the investigation needs to come from outside the system it’s examining.

The HR team has a conflict of interest. If HR is friends with the respondent, reports to the person being complained about, or has been part of the problem, they cannot investigate it. Full stop.

The Psychosocial Safety Dimension

Under current WHS laws, employers have a positive duty to manage psychosocial risks in the workplace. The way you conduct a workplace investigation has a direct impact on the psychological safety of everyone involved.

An investigation that’s perceived as biased, that takes too long, or that’s conducted by someone too close to the situation doesn’t just produce unreliable findings – it actively harms the people involved. The complainant feels dismissed. The respondent feels targeted. The rest of the team loses faith in the organisation’s ability to keep them safe.

Choosing between an internal and external investigation isn’t just a procurement decision. It’s a workplace safety decision. And it should be treated with that level of seriousness.

The Bottom Line

There’s no one-size-fits-all answer to the external vs. internal workplace investigation question. But there is a simple test: if you have any doubt about whether an internal investigation will be trusted, believed, and respected by the people involved, bring in someone from outside.

The cost of an external investigator is predictable and contained. The cost of an investigation that nobody trusts – in legal fees, staff turnover, compensation claims, and cultural damage – is not.

Need an independent, external workplace investigation? Segal Conflict Solutions provides external workplace investigations in Sydney and across Australia, delivering thorough, impartial findings your organisation can rely on. Get in touch for a confidential discussion.

If you’re Googling “how long do workplace investigations take,” I’m going to guess you’re in one of two camps. Either you’re the employer who just received a complaint and you’re trying to figure out how long your life is going to be disrupted. Or you’re the person who made the complaint and you’re wondering why it feels like everyone has forgotten about you.

Either way, you want a number. So here it is.

The Short Answer

Most workplace investigations take between 2 and 8 weeks. Some wrap up faster. Some drag on for months. I know that’s not the precise, satisfying answer you were hoping for, but workplace investigations aren’t flat-pack furniture  – they don’t come with a predictable assembly time.

What I can tell you is what determines whether your investigation lands at the shorter or longer end of that range. And as someone who’s conducted numerous workplace investigations for over 15 years, I can tell you the factors that blow out timelines are almost always avoidable.

What Actually Affects the Timeline

1. The Complexity of the Complaint

A single allegation of inappropriate behaviour with two witnesses? That’s a relatively contained investigation  – potentially 1–3 weeks. Six allegations of bullying spanning two years with twelve witnesses and a paper trail that looks like it was shredded and reassembled by a toddler? You’re looking at 6–8 weeks minimum.

The scope of the investigation is the single biggest factor in how long it takes. More allegations mean more witnesses, more documents to review, and more findings to write up. It’s not complicated maths  – it’s just reality.

2. Witness and Party Availability

This is the timeline killer that nobody talks about. I can have my diary cleared and ready to go, but if your key witness is on annual leave in Bali for two weeks, we’re all waiting. If the respondent is on stress leave and their doctor says they can’t participate for a month, we’re waiting for that too.

People also cancel interviews. Reschedule. Get sick. Have family emergencies. These are humans, not calendar entries, and investigations have to work around real lives. I’ve had investigations delayed by weeks because one critical witness kept rescheduling.

3. How Quickly the Organisation Moves

Here’s a hard truth: the biggest delays in workplace investigations usually come from the organisation itself, not the investigator.

I regularly see weeks lost to internal decision-making. Who should we appoint? Do we need an external investigator? Should we get legal advice first? Should we wait until after the restructure? Meanwhile, the complainant is sitting at their desk every day wondering if anyone actually read their complaint.

My advice? Once you receive a complaint, make a decision within 48 hours about how you’re going to handle it. That doesn’t mean you start interviews immediately  – it means you decide on your approach, appoint your investigator, and communicate with the parties. Speed at this stage sets the tone for the entire process.

4. The Volume of Documents

Some investigations involve a handful of emails. Others involve hundreds of documents  – emails, text messages, CCTV footage, performance reviews, policy documents, and the complainant’s own 47-page diary of events (yes, this happens more than you’d think).

Document review takes time. Good investigators don’t skim  – they read everything, cross-reference it, and use it to inform their interview questions. If you want a thorough investigation, you need to factor in time for this.

5. Procedural Fairness Requirements

This is non-negotiable and it adds time. Every person against whom allegations are made has the right to know what’s been alleged and to respond. This isn’t optional  – it’s a legal requirement under Australian workplace law, and skipping it is one of the fastest ways to have your investigation findings thrown out.

What does this look like in practice? The investigator interviews the complainant first, then puts the key allegations to the respondent  – often in writing  – and gives them a reasonable time to respond. The respondent’s response is then considered before any findings are made. This process is important and non-negotiable, but it adds at least a week or two to most investigations.

A Realistic Timeline: What Each Phase Looks Like

Here’s roughly how a standard workplace investigation breaks down:

Scoping and planning (2–5 days): Defining the terms of reference, identifying witnesses, gathering initial documents, and getting the logistics sorted.

Interviews (1–4 weeks): The most variable phase. Depends entirely on how many people need to be interviewed and how available they are. Each interview typically runs 1–2 hours, and the investigator needs time to prepare, conduct, and write up notes for each one.

Document review and analysis (3–7 days): Often happens concurrently with interviews, but complex matters may need dedicated time for this.

Procedural fairness (1–2 weeks): Putting allegations to the respondent and allowing them time to respond.

Report writing (1–2 weeks): Preparing a detailed investigation report with findings and, where appropriate, recommendations. This isn’t a rush job  – a good report needs to be thorough, well-reasoned, and legally sound.

Red Flags: When an Investigation Is Taking Too Long

While some investigations legitimately take longer, there are warning signs that something has gone wrong:

If it’s been more than two weeks and nobody has been interviewed yet, ask questions. If you haven’t received any update in three weeks, that’s a problem. If the investigation has been going for three months with no end in sight, something is fundamentally broken  – either the scope has ballooned, the investigator is overwhelmed, or the organisation is dragging its feet.

Delays aren’t just inconvenient  – they’re harmful. For the complainant, every extra week feels like the organisation doesn’t care. For the respondent, it’s weeks of having allegations hanging over their head. And for the rest of the team, it’s weeks of tension, gossip, and uncertainty. Dragging out investigations costs organisations far more than just the investigator’s fees.

The Psychosocial Risk Factor: Why Timeline Matters More Than Ever

If you haven’t been paying attention to the changes in workplace health and safety laws, now’s the time to start. Under the updated WHS regulations, employers have a positive duty to identify and manage psychosocial hazards in the workplace. And unresolved complaints? Investigations that drag on without communication or resolution? Those are psychosocial hazards.

Think about it. A complainant who’s raised a bullying allegation and heard nothing for six weeks is sitting in a psychologically unsafe workplace every single day. A respondent with allegations hanging over their head and no indication of when it’ll be resolved is experiencing chronic workplace stress. The rest of the team, walking on eggshells because they know something is going on but nobody’s telling them anything? That’s a toxic work environment brewing in real time.

This means the timeline of your investigation isn’t just an operational issue  – it’s a safety issue. Regulators like SafeWork are increasingly looking at how employers manage the process around complaints, not just the outcome. A substantiated finding delivered six months late, with no interim risk management, no communication, and no support for the parties? That’s a failure, even if the final report is excellent.

What does this mean practically? It means that while the investigation is underway, employers need to be actively managing the psychosocial risks created by the situation. That might include adjusting reporting lines, offering EAP support, checking in with affected parties, or making temporary changes to work arrangements. The investigation doesn’t happen in a vacuum  – people still have to come to work every day while it’s going on, and they need to feel safe doing so.

How to Keep Your Investigation on Track

After years of doing this, here’s what I know works:

Act quickly once a complaint is received. Don’t let it sit in someone’s inbox for two weeks while you figure out what to do. Appoint an investigator, set terms of reference, and get moving.

Decide early whether to go internal or external. This is one of the first decisions you need to make, and it matters more than people think. If the complaint involves senior leadership, if there’s any perception of bias, or if your HR team is too close to the parties involved, an internal investigation is going to struggle for credibility – no matter how well it’s conducted. Trust in the process is everything. If the people involved don’t believe the investigation is independent and impartial, your findings won’t be worth the paper they’re written on. When in doubt, go external. The cost of an external investigator is nothing compared to the cost of an investigation nobody trusts.

Choose the right investigator from the start. An experienced workplace investigator will scope the investigation properly, manage the process efficiently, and not let things drift. If your investigator doesn’t give you a rough timeline at the outset, ask for one.

Make witnesses available. This is the employer’s responsibility. Direct witnesses to cooperate and make themselves available for interviews within a reasonable timeframe.

Have your documents ready. When the investigator asks for policies, employment records, or emails, get them across quickly. Every day you take to find documents is a day added to the timeline.

Communicate with the parties. Regular updates, even if it’s just “the investigation is ongoing and we expect it to be completed by nominated date,” go a long way toward managing expectations and maintaining trust in the process.

The Bottom Line

A well-run workplace investigation should take weeks, not months. If your investigation is dragging on indefinitely, the problem is rarely the complexity of the matter  – it’s the process around it.

Get the right investigator, give them what they need, and hold everyone accountable for keeping things moving. Your people deserve a timely resolution, and your organisation deserves findings it can actually rely on.

Need a workplace investigation conducted properly and efficiently? Segal Conflict Solutions provides independent, external workplace investigations in Sydney and across Australia. Get in touch for a confidential discussion about your matter.

Not all conflict shows up as a formal complaint. Some of it lurks in the background. It hides behind passive-aggressive comments, awkward silences in team meetings, and a subtle shift in energy that no one can quite name-but everyone feels. And often, by the time it’s officially escalated to HR or leadership, the damage is […]