A contract takes two people to make and two to change
The answer is simpler than the situation usually feels. gov.uk states it directly: usually, the employer and employee both need to agree to any contract changes.
That reads as obvious and it is not how most people experience it, because a change to hours, duties, location or pay almost always arrives as an announcement rather than a proposal. An employer is expected to consult or negotiate, and to explain the reasons, before anything moves.
So imposing a change without agreement is a breach of contract rather than a management decision that has to be absorbed. Whether it is worth doing anything about is a separate question, and the answer to that one is not automatic either.
A flexibility clause is the start of the argument
Plenty of contracts contain a clause allowing the employer to vary something: duties, location, hours. Those clauses do work, and they are read far more narrowly than the people relying on them expect.
A clause permitting a change of duties is not usually read as permission to cut pay or to rewrite the job into something else. A clause drawn broadly enough to allow anything at all tends to attract more suspicion rather than less, precisely because of how broad it is. And there is a general expectation that a contractual power is exercised reasonably rather than arbitrarily.
Four responses, and they are not steps
That last panel is the one worth taking away. Continuing to work changed terms without objecting can, over time, be treated as having accepted them, and the longer it runs the harder that gets to argue with.
Which is why the standard move for somebody who disagrees but cannot stop working is to say so clearly and in writing, and carry on. The record then shows the position instead of implying the opposite.
Fire and rehire is not banned, it is constrained
Where agreement cannot be reached, an employer may dismiss and offer re-engagement on new terms. That is still lawful and it now has a statutory code sitting over it.
The Code of Practice on Dismissal and Re-engagement came into force on 18 July 2024 and sets out that the approach should be a last resort after genuine consultation rather than a negotiating tactic.
The enforcement is financial and it is significant. An employment tribunal can increase an award by up to 25 per cent where an employer has unreasonably failed to comply with the code. The same power runs both ways and can reduce an award by up to 25 per cent where it is the employee who has unreasonably failed to comply.
Most guidance written before mid-2024 does not mention any of this, which is worth knowing if you are reading around the subject.
What this page will not tell you
Whether a particular change is lawful, and what you should do about it. Both turn on your actual contract, what was agreed at the start, what has been said since and what has happened in practice, and none of that is knowable from here.
Resigning and claiming constructive dismissal is a route that exists and it is genuinely risky: you have to be right about the breach, and you have given up the job in order to argue about it. Nobody should take that step on the strength of a free web page.
Acas is free and is the place to go, or the Labour Relations Agency in Northern Ireland. Acas early conciliation is a required step before most tribunal claims in any case. In the meantime, keep the paperwork and write down the dates and the conversations while they are fresh, because that record is the whole of the evidence later.
The documents underneath all this
Whatever is being changed, the starting point is what the terms actually are. The employment contract builder covers the written statement and the headings the law requires, including the ones added in 2020 that older contracts simply do not have.
If the change is to hours, the 48-hour check covers the averaging and the opt-out, and holiday entitlement recalculates when a pattern changes. If the arrangement is ending rather than changing, notice period and holiday pay on leaving are the two that decide what is owed. And if the underlying question is which rights you have at all, employee, worker or self-employed comes first.
Common questions
Can my employer just change my hours or pay?
Not unilaterally, as a rule. gov.uk puts it plainly: usually, the employer and employee both need to agree to any contract changes. An employer is expected to consult or negotiate and to explain the reasons for the change rather than announce it. That does not mean a change can never happen, and it does mean imposing one without agreement is a breach of contract rather than a management decision the employee simply has to absorb.
What if my contract has a flexibility clause?
It may allow the change, and these clauses are read far more narrowly than employers expect. A clause letting an employer vary duties or location is not usually read as permission to cut pay or fundamentally rewrite the job, and a clause broad enough to allow anything tends to be treated with suspicion precisely because of how broad it is. There is also a general expectation that any such power is used reasonably rather than arbitrarily, so having a clause is the beginning of the argument rather than the end of it.
What happens if I just refuse?
Several things can follow and they are not sequential steps, they are different routes with different consequences. The change may be dropped or renegotiated. The employer may impose it anyway, which is a breach you can object to in writing while continuing to work. It may lead to a dismissal and an offer of new terms. What you should not do is carry on silently for months, because saying nothing while working the new terms can be treated as having accepted them.
Is fire and rehire still allowed?
It is not banned and it is constrained. A statutory Code of Practice on dismissal and re-engagement came into force on 18 July 2024, and it sets out that the approach should only be used as a last resort after genuine consultation. The enforcement is financial: an employment tribunal can increase an award by up to 25 per cent where an employer has unreasonably failed to comply with the code. The same power runs the other way and can reduce an award by up to 25 per cent where the employee has unreasonably failed to comply.
Can working under the new terms mean I have accepted them?
It can, which is why silence is the riskiest response available. Continuing to work changed terms without objecting, over a period, may be treated as acceptance by conduct, and the longer it runs the harder it is to argue otherwise. If you do not agree with a change but cannot afford to stop working, the usual approach is to say so clearly in writing and keep working under protest, so that the record shows the position rather than implying agreement.
Where do I go if this is actually happening?
Acas, in England, Scotland and Wales, or the Labour Relations Agency in Northern Ireland. Both are free, and Acas early conciliation is a step that has to happen before most tribunal claims anyway. Nothing on a web page can tell you whether a particular change is lawful, because it turns on your actual contract, what was agreed, what was said and what happened. What is worth doing immediately is keeping the paperwork and writing down dates while they are fresh.