Two staff have fallen out. Must I move one?

Alan Creevy, Founder · 22nd October 2026

“Move him to another team” is a reasonable thing for an employee to ask and often an impossible thing for you to give. In a business of nine people there is no other team. There is one rota, one van, one office, and the two of them have to be in it together on Monday.

So the useful question is not where to put anyone. It is what you are actually holding. A falling out between two colleagues and a complaint about how one of them has been treated look identical on arrival, and they put very different obligations on you. Get that wrong and the move itself becomes the thing you end up defending.

Work out whether you have been handed a grievance

Nobody has to use the word grievance, or put anything in writing, for this to count. Acas is clear that if a worker raises a problem informally you should still take it seriously. “I can’t work with him any more” might mean two colleagues who have stopped getting on. It might also be an allegation that his behaviour towards her has been offensive or intimidating, which is what Acas describes as bullying, and which engages what it calls your legal duty of care to protect workers from harm.

The fastest way to find out is to ask. Is this a complaint you want me to look into, or do you want help working alongside someone you no longer get on with? Then write the answer down, with the date. If she wants it looked into, you are holding a grievance whatever either of you calls it, and the Acas Code of Practice expects a formal meeting “without unreasonable delay” after it is received (paragraph 33), a companion if she wants one (paragraph 35), and the decision in writing with a right of appeal (paragraph 40). Five working days to the meeting and three more to the written outcome keeps you comfortably inside that, and the free disciplinary timetable will put dates on the steps for you.

If a protected characteristic is anywhere near this, it is not a falling out

Listen for what the behaviour was about, not only how bad it was. Harassment under section 26 of the Equality Act 2010 is unwanted conduct related to a protected characteristic, which here means age, disability, gender reassignment, race, religion or belief, sex or sexual orientation, where it has the purpose or effect of violating someone’s dignity or creating an intimidating, hostile, degrading, humiliating or offensive environment for them. Comments about someone’s accent, age, faith or sex are not a personality clash, however long the two of them have been needling each other.

Two things follow. The first is that an informal fix is no longer enough on its own: you need to establish what happened and deal with it, because a quiet reshuffle leaves the conduct unaddressed. The second is the standard. Since 30th October 2026 the duty on employers to prevent sexual harassment has been a duty to take all reasonable steps rather than reasonable steps, so “we moved them apart and it stopped” will be measured against every step you could reasonably have taken, including the ones you did not think of.

Moving someone is a change to their job, so check the contract before you offer it

Where someone works, who they report to and what they do are usually contractual. Both gov.uk and Acas say the same thing about changing them: you need the employee’s agreement. A mobility or flexibility clause may give you room on location or duties, so read the contract first, but treat a clause as permission to ask, not cover for presenting someone with a fait accompli. Dismissing someone and taking them back on new terms is something Acas tells employers to avoid, and it is expected to become automatically unfair, with 1st January 2027 the intended date once the regulations are made.

In practice you offer, in writing, and you make the choice explicit. “I can move you onto the Tuesday to Thursday rota next week if you’d prefer, and that’s your choice” is a different conversation from “you’re going on the other rota”.

Whatever else you do, do not move the person who complained

Acas is firm about this. Its guidance on handling a formal complaint says you should not move the person who made the complaint unless they ask to be moved, because doing it when they have not asked could be seen as a punishment for complaining. If anybody is moved for good, it should be the person whose behaviour is in question, and only once you know enough to say whose behaviour it was.

The reason is victimisation. Under section 27 of the Equality Act 2010, subjecting someone to a detriment because they made an allegation that the Act has been contravened is unlawful, and Acas defines detriment simply as being treated worse than before or having their situation made worse. Taking her off the better shifts or out of the team she trained in is a detriment, and her asking for him to be moved is not consent to being moved herself.

While you look into it, the same Acas guidance accepts that you may need to separate them, as long as any temporary move is done fairly. If you cannot tell yet whose conduct is in question, move the arrangement rather than a person. Change who covers which jobs, split the rota, put the handover in writing, take one of them off the shared task for a fortnight. Say in writing that it is temporary, why you have done it, and when you will review it. That is an interim arrangement, not a verdict, and it reads very differently later than a permanent move imposed on one of them in week one.

Mediation is the right tool for this, and it has limits

For a relationship that has broken down over how work gets done, mediation is what Acas points to. It is voluntary, confidential, and focused on how the two of them work together in future rather than on who was right. Acas names personality clashes and relationship breakdowns as what it is for, and says to start as soon as you can.

Acas says mediation is generally not used for disputes about pay, dismissal or conduct. So if one of them is alleging that the other behaved unacceptably, mediation is not a substitute for finding out whether that happened. Investigate first, mediate afterwards if there is a working relationship worth rebuilding. In a small firm you may find you have nobody neutral to investigate, which is its own problem and one worth reading up on separately.

Leaving it costs something too. In Acas research published in 2025, 44% of workers reported some form of conflict in the previous year, a third of those said theirs was mainly or completely unresolved, and 57% of people who reported conflict said it led to stress, anxiety or depression. If it ends with one of them going off sick, that is a harder situation again.

What to do today

Speak to the person who asked for the move today and establish one thing: is she asking you to deal with something that was done to her, or asking for help working alongside someone she no longer gets on with. Note the answer and the date.

If it is the first, start a grievance, tell her that is what you are doing, and get the dates in the diary. If it is the second, offer mediation to both of them and say plainly that it is voluntary. Either way, pull out both contracts and see what you can actually offer on location, duties and hours before you offer anything.

Then make any immediate change to the arrangement rather than to the person who complained, put it in writing as temporary with a review date, and keep the note. In three months the only record will be what you wrote at the time, and the question will be why you did what you did on the day you did it.

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.