A grievance about the manager investigating them

15th October 2026

You are partway through investigating a disciplinary matter, and the employee has put in a grievance about the manager doing the investigating. There are two wrong moves available to you this week, and the second one is the one that looks sensible. The first is to carry on as though the complaint had never landed. The second is to stop everything, say nothing and wait for the grievance to sort itself out.

Neither is what the Acas Code asks of you, and neither is what a tribunal would look for afterwards. What it would look for is a decision about how the two things run alongside each other, taken on purpose, with a note saying why you took it.

Work out which of three complaints you are holding

Read it again and decide which of these it is.

A complaint about the investigation itself. You have made your mind up, you only spoke to one person, you have not shown them the evidence, you took the complainant at their word. This is a process complaint, and most of the time you can put it right inside the disciplinary rather than outside it.

A complaint about the manager as a manager, with the investigation as the trigger rather than the subject. Bullying, favouritism, something that happened in March. That is a grievance in its own right and it needs its own process and its own person.

An allegation of discrimination, harassment or retaliation. It may not use those words. Treat it as this kind if the substance is there, because the legal consequences follow the substance, not the label.

If you cannot tell, ask them in writing what outcome they are looking for.

You can keep going, but you have to choose

The Acas Code of Practice on disciplinary and grievance procedures deals with this in a single paragraph. Paragraph 46 says that where an employee raises a grievance during a disciplinary process “the disciplinary process may be temporarily suspended in order to deal with the grievance”. Where the two are related, it adds, “it may be appropriate to deal with both issues concurrently”. Acas says the same in its guidance on following a fair disciplinary procedure.

May, not must. The choice is yours, and so is the job of justifying it. Pause if the grievance, were it true, would change how the investigation has been run or who should be running it. Run the two together if they are two sides of the same incident and you can keep the roles clean. What you cannot do is leave it undecided for three weeks while the investigation quietly continues.

Write a short note the same day saying what they alleged, which route you have taken and why. Add when the disciplinary will restart. Four sentences is enough. That note is the most useful piece of paper in the file, because it shows you thought about it at the time rather than in hindsight.

The manager complained about should not answer the complaint

Acas is clear on this in general terms. Its guidance on preparing for an investigation says the employer “should get somebody who’s not involved in the case to carry out the investigation”, to make sure there is no conflict of interest. Paragraph 6 of the Code adds that in misconduct cases, “where practicable, different people should carry out the investigation and disciplinary hearing”.

None of that tells you what to do when the uninvolved person does not exist, which is the position most small employers are in.

When there is nobody else

Work down this list and stop at the first one you can actually do.

Another director, owner or partner, even one who is not usually involved in staff matters. Then a manager from a different part of the business, even a more junior one, as long as you give them the authority to decide and then honour what they decide. Then someone from outside: the same Acas guidance says that in exceptional circumstances it might be appropriate to appoint an external consultant, who can be more detached and bring an independent view, though it costs more and takes longer. If your business insurance includes employment cover, check whether it comes with an advice line before you pay for one.

If none of those is available, split the roles rather than abandoning them. The person complained about may have to finish gathering the facts, but somebody else decides. Where an uninvolved investigator is not possible, Acas says the employer should “try and make the procedure as impartial as they can”.

Then tell the employee what you have done and why, in writing, before the next meeting. Leaving the manager who is the subject of a grievance to decide its outcome is the version of this that is hardest to explain afterwards.

If the allegation is discrimination, the risk changes shape

Making an allegation, express or not, that someone has contravened the Equality Act is a protected act under section 27 of the Equality Act 2010. Subjecting someone to a detriment because they have done that is victimisation, and it is a separate claim from whatever the disciplinary was about. The protection is lost only where a false allegation is made in bad faith, so an honest complaint that turns out to be wrong is still protected.

In practice the disciplinary outcome has to be the outcome you would have reached before the grievance arrived, and you need to be able to show that. Keep the dates straight in the file. A warning that hardens into a dismissal in the week after a discrimination complaint is going to need an explanation that does not depend on your memory. A dismissal also carries more risk from next year: from 1st January 2027 the qualifying period for ordinary unfair dismissal is due to fall from two years to six months, which we cover in unfair dismissal at six months.

If the grievance is about sexual harassment, the law tightens on 30th October 2026. According to Acas’s tracker of the Employment Rights Act 2025, the existing duty to take reasonable steps to prevent sexual harassment of your workers will become a duty to take all reasonable steps. From the same day, employers will be liable for harassment of their staff by third parties, such as customers or clients, unless they have taken all reasonable steps to prevent it. A grievance about harassment is not a side issue to the disciplinary.

Timing, and the part that costs money

The Code asks for a formal grievance meeting “without unreasonable delay” at paragraph 33, a written decision without unreasonable delay at paragraph 40 and the same for appeals at paragraph 42. There is no number attached to any of them. Around five working days from the invitation to the meeting and three more to the written outcome is a defensible rhythm for a small business. Those are the starting figures in our free disciplinary and grievance timetable, which maps the dates and lets you change each gap.

The employee can bring a trade union representative or a colleague to a grievance hearing if they reasonably ask to, under section 10 of the Employment Relations Act 1999. The right attaches to each hearing, so offer it again in the grievance invitation even if you offered it for the disciplinary.

An unreasonable failure to follow the Code lets a tribunal increase an award by up to 25%, under section 207A of the Trade Union and Labour Relations (Consolidation) Act 1992. That is a percentage of the compensation itself, which is why a tidy file is worth more than a clever argument.

Keep the file for longer than you used to, as well. Tribunal time limits rose from three months to six on 1st October 2026, where the relevant date falls on or after that day, so your notes now have to make sense to a stranger half a year later.

What to do today

Send a short acknowledgement confirming you have received the grievance, that you are dealing with it and when they will hear from you. Decide whether you are pausing the disciplinary and write down why. Identify who is taking the grievance and, if that changes who decides the disciplinary, say so. Then invite them to a grievance meeting about five working days ahead, with the right to be accompanied set out in the invitation. Our grievance hearing invitation letter template has the wording.

If you are the only manager there is, the same problem comes up from the other direction when somebody reports a colleague to you. We cover it in someone has told me an employee is stealing.

Tarn.hr provides HR guidance based on UK employment law and Acas codes of practice. It does not constitute legal advice and should not be relied upon as such. Employment law is complex and turns on the facts of each case. For any situation involving significant legal risk, potential tribunal claims, or matters of particular sensitivity, you should seek advice from a qualified employment solicitor. Tarn.hr is not responsible for any decisions made on the basis of its guidance.