Usually not on their own. Your working hours are normally part of your contract, so your employer needs your agreement to change them. The main exception is a clause in your contract that lets them make the change, and even then the change has to be reasonable and your employer should tell you in advance. This article covers England and Wales.
Why Your Contract Decides it?
Your working hours are usually written into your contract or your written terms of employment. Changing them is a change to the contract, which is why Citizens Advice lists hours and shift patterns, alongside pay, holiday and place of work, as the kind of change an employer should only make in limited ways.
Your contract may not tell the whole story. Working Families says that a long-standing working pattern your employer has approved can become part of your contract even if it was never written down, while a short-term arrangement usually does not. If your actual hours have been different from your written ones for a long time, say so when you raise the issue.
When Your Employer Can Change Your Hours?
According to Citizens Advice, an employer should only change your contract in one of three situations:
- You agree to the change
- Your contract has a variation clause that allows it
- The law is changing, for example a rise in the National Minimum Wage
Agreement does not have to be a signature. If you carry on working the new hours without objecting, your employer may say you accepted them. That is why objecting early matters, and it is covered below.
What a Flexibility or Variation Clause Allows?
Many contracts say the employer can change your hours “to meet the needs of the business” or something similar. These are often called flexibility, variation or mobility clauses.
A clause is not a blank cheque. Citizens Advice says an employer cannot rely on a variation clause if the change is unreasonable or is being introduced without notice, and gives the example of a change that makes caring responsibilities difficult. Working Families adds that a clause has to be specific, and that broad wording usually covers only minor changes that do not leave you worse off.
The same approach applied in a case about moving workplace. In Kellogg Brown & Root (UK) Ltd v Fitton and Ewer, the Employment Appeal Tribunal upheld a finding that two employees were unfairly dismissed after refusing to relocate, because the mobility clause was too wide and uncertain and the instruction was unreasonable. As Doyle Clayton explains, that case concerned an office move and not working hours, so it shows how a tribunal treats wide clauses and not a rule on hours.
Types of Change to Working Hours
The rules depend on what changes. These are the points to check for each kind of change.
| Change | What to check |
|---|---|
| Different shift pattern or rota | Whether your contract fixes your hours, and whether a variation clause covers a change of pattern |
| Fewer hours | Whether your pay drops with them. A pay cut not covered by your contract may support a claim for unauthorised deductions from wages |
| More hours | Whether your contract sets your hours or requires overtime |
| Day work to night work, or weekdays to weekends | The new fire and rehire rules, once in force, treat these as restricted changes (see below) |
| A small change to start or finish times | Whether your contract or a clause allows it, and whether it is reasonable for you |
If a change in hours means a change in pay, you can also read about your rights if you get a low paycheck.
Can my Employer Change my Hours Without Notice?
If your employer relies on a variation clause, Citizens Advice says they should tell you in advance, and they cannot rely on the clause if the change is introduced without notice. Citizens Advice does not give a fixed number of days for the notice, so look at what your contract says and at how much time you have been given to plan around the change.
Without a clause, your employer needs your agreement, and an announcement is not agreement.
What to Do if You Disagree With the New Hours?
Citizens Advice suggests these steps if you do not want to accept a change:
- Tell your employer in writing, as soon as you learn of the change, that you are working “under protest”
- Say clearly that you do not accept the change and ask for the reasons
- Suggest alternatives that could meet your employer’s needs
- Try to resolve it quickly, because working for a long time without agreeing may still be taken as agreement
Before you object, read your contract for any clause on hours, flexibility or variation. If you ask for a different arrangement through a flexible working request, Working Families warns that a request can be read as accepting your employer’s proposal, so say in writing that you do not accept the change.
If the change affects you because of something like sex, disability or caring responsibilities, tell an adviser. A change that treats you worse because of a protected characteristic can be discrimination, and Working Families notes that a change which disadvantages women because of childcare can be indirect sex discrimination unless the employer can justify it.
What Happens If I Refuse?
Refusing a change can lead to disciplinary action or dismissal. Whether it is justified depends on the reason and the process. As the guide to insubordination explains, a refusal is not insubordination just because you disagree: it depends on whether the instruction was lawful, reasonable and within your contractual duties.
If you are dismissed for refusing, you may be able to claim unfair dismissal, though Citizens Advice says that can be difficult if your employer had a good business reason. Unfair dismissal claims normally need two years’ continuous service. The government intends to cut that to six months from 1 January 2027 under the Employment Rights Act 2025, according to Browne Jacobson. Check the current position before relying on either figure.
Constructive Dismissal and Time Limits
You can resign and claim constructive dismissal, but it is hard to prove. Citizens Advice says it is “very difficult to prove constructive dismissal” and suggests considering whether to stay in the job while you look for another one.
The test under section 95(1)(c) of the Employment Rights Act 1996, as Magrath explains, has three parts:
- Your employer’s conduct must be a serious breach of your contract
- You must resign because of the breach
- You must act promptly, because waiting too long can be treated as accepting the breach
Magrath adds that raising a grievance before resigning is advisable. A change to your hours imposed without agreement can be a breach, but whether it is serious enough depends on the facts.
Time limits have changed. ACAS says that for problems before 1 October 2026, most claims have 3 months less a day, and for problems on or after 1 October 2026, most claims have 6 months less a day. The deadline normally runs from the date of the problem, or for unfair dismissal from the last day of your employment. If you notify ACAS for early conciliation within the time limit, the clock is paused, but only if you notify before the limit runs out. Older guides still say three months, so check the date of your change.
Fire and Rehire and Changes to Hours
“Fire and rehire” means dismissing an employee and offering them a new contract on different terms. The Employment Rights Act 2025 will make this automatically unfair where the reason is a “restricted variation”, except in cases of financial difficulty. According to Browne Jacobson, restricted variations include:
- Reducing pay or certain other entitlements
- Reducing holiday entitlement
- Changes to pensions
- Changes to hours or shifts, including moving between day and night work or between weekdays and weekends (night is 11pm to 6am)
- Adding a variation clause that lets the employer make these changes without your approval
The same article says that changes to availability windows and minor shift changes, such as moving a daytime shift back a few hours, are not restricted. It gives the implementation date as March 2027, delayed from January 2027, as of 28 October 2026. Some firms still show January 2027, so check the current position.
Until the new rules start, Citizens Advice says employers should follow the government’s code of practice on dismissal and re-engagement, giving you the proposed changes, their reasons and alternatives in writing before deciding.
Common Questions & Answers
Not safely. If they rely on a variation clause, they should tell you in advance and cannot rely on the clause if the change comes without notice. Without a clause, they need your agreement.
Only if you agree or your contract allows it. Check your contract for a flexibility or variation clause, and for what it says about your hours. Even with a clause, the change has to be reasonable.
Only if you agree or your contract allows it. A pay cut that your contract does not cover may support a claim for unauthorised deductions from wages.
You can say you do not accept them, ideally in writing and under protest. Refusing can lead to disciplinary action, so take advice before you stop working the new hours.
Possibly, but it is hard to prove and you normally need two years’ service. You must show a serious breach, resign because of it, and act promptly. Raising a grievance first is advisable, and you should take advice before resigning.
It can be treated that way, especially if you carry on for a long time without objecting. Tell your employer in writing that you are working under protest as soon as you learn of the change.
