Somewhere between 30% and 40% of UK employees will raise a formal grievance at some point in their careers. Most do it badly, or their employer handles it badly and both parties end up at an employment tribunal wondering how it came to this. It rarely has to.
Here’s the practical UK workplace grievance guidance you should read.
What a grievance actually is
A grievance is a formal complaint about something at work. The classics: bullying, harassment, discrimination, unfair treatment, pay disputes, unsafe conditions, or the way a disciplinary process is being run against you.
The legal backbone is the ACAS Code of Practice on Disciplinary and Grievance Procedures. It’s not statute, but it might as well be. Tribunals are legally required to take it into account, and if your employer unreasonably fails to follow it, a tribunal can increase any compensation you win by up to 25%. If you unreasonably fail to follow it, your award can be cut by up to 25%. The Code cuts both ways — which is why knowing it matters before you type that angry email.
Step one: try to sort it out informally (but don’t be bullied into it)
The Code encourages informal resolution first. Sometimes that’s exactly right; a quiet word with your manager clears up a misunderstanding that a formal process would only inflame. Mediation, where a neutral third party facilitates a conversation, works surprisingly well for personality clashes and working relationships gone sour.
But here’s the bit employers often conveniently forget: you have the right to go formal at any time. If your manager suggests you “don’t need to make this official,” ask yourself whether they’re trying to resolve the problem — or make it disappear. A grievance is not a declaration of war; it’s a legal process you’re entitled to use.
Step two: put it in writing
A formal grievance should be written and should include:
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What the problem is, in specific terms (dates, events, people involved)
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When it happened
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How you’d like it resolved — this matters more than people realise
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What you’ve already tried informally, or why you haven’t
That last point is getting more formal emphasis. ACAS is currently consulting on a revised draft Code of Practice (launched mid-2026), which would make it an explicit expectation — not just an allowance — for workers to say how they’d like their concern resolved when they raise it, and to state what informal steps they’ve already taken. The aim is to push both sides toward practical resolution rather than procedural trench warfare. The final Code is expected to take effect alongside the wider Employment Rights Act 2025 rollout, so it’s worth watching.
A short, clear letter is fine. You don’t need to write a legal essay. In fact, a focused two-page grievance is often more effective than a twenty-page one.
Step three: what your employer must then do
Once the grievance lands, the employer’s obligations are:
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Arrange a formal meeting without unreasonable delay. Vague timescales are a classic stalling tactic, “we’ll look into it” followed by silence is not compliance with the Code.
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Let you be accompanied. Under section 10 of the Employment Relations Act 1999, you have a statutory right to bring a trade union representative or a work colleague to any formal grievance hearing. They can address the meeting, put your case, sum up and confer with you, though they can’t answer questions on your behalf. Your employer cannot take this right away, and they can’t insist on a solicitor instead (nor are you entitled to one as of right).
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Investigate properly. Someone impartial, ideally not the person your grievance is about- should look into the facts, speak to witnesses, and gather evidence.
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Decide, and tell you in writing. The outcome must be communicated in writing without unreasonable delay, with reasons, and with confirmation of your right to appeal.
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Offer a genuine appeal. Heard by someone who wasn’t involved in the original decision, ideally more senior. An appeal to the same manager who dismissed your grievance is a box-ticking exercise, and tribunals see through it.
The mistakes that sink grievances
For employees: raising everything at once (kitchen-sink grievances lose credibility), going in with no idea what outcome you want, refusing to attend meetings, and sitting on it for months. On that last point, from October 2026, the time limit for bringing an employment tribunal claim has doubled to six months, but even that isn’t a reason to wait.
For employers: pre-judging the outcome, letting the person the grievance is about investigate it, leaking details to people who don’t need to know, retaliating against the person who raised it (that’s victimisation, and it’s unlawful), and treating the grievance as an inconvenience rather than a legal obligation. From 1 January 2027, the unfair dismissal qualifying period drops to six months and the compensation cap is removed entirely, meaning procedural sloppiness around grievances will carry far bigger financial exposure than it used to. The era of the low-stakes tribunal claim is ending.
When grievance and disciplinary collide
A common and messy scenario: you’re facing a disciplinary and simultaneously have a grievance about how that disciplinary is being conducted. ACAS guidance is that if your grievance relates to the disciplinary process itself — you allege bias, say — the employer should consider pausing the disciplinary to deal with the grievance first. If the grievance is unrelated, the two can run in parallel. Either way, the employer should document its reasoning. If they plough on regardless while ignoring your grievance, that’s a point you can raise, at appeal, and later at tribunal.
The bottom line
The grievance procedure is not a formality and it is not optional window-dressing. It’s the single most important procedural protection most employees will ever use short of a tribunal claim itself and increasingly, with the ERA 2025 changes taking effect through 2026 and 2027, tribunals will care more, not less, about whether it was followed properly on both sides.
If you’re an employee: raise it early, put it in writing, say what you want, and keep notes of everything. If you’re an employer: treat every grievance as if it will one day be Exhibit A, because with uncapped awards on the horizon from January 2027, it very well might be.
And if things have gone too far for the internal process, the first stop is ACAS early conciliation — which you’ll need to go through before any tribunal claim anyway. Six months sounds like a long deadline. It goes faster than you think.
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