TL;DR: Too long, Didn’t read
Check Your Contract: Most contracts have a “flexibility clause” allowing changes, but they must be reasonable.
Reasonable Notice: Even if the contract allows changes, your employer usually must give you “reasonable notice” (often defined as 12-24 hours, but it depends on your industry).
The “On-Call” Trap: Unless you are paid to be “on-call,” you usually don’t have to sit by the phone waiting for work.
You Can Refuse: If the change makes it impossible for you to work (e.g., childcare or medical appointments), you can often refuse on the grounds of “unreasonable request.”
It’s Sunday night. You have planned your week. Then your phone buzzes. It’s your manager: “Need you in tomorrow at 8am instead of 2pm.” Or worse, you turn up to work and they send you home because it’s “quiet.”
Is this legal? Do you have to say yes?
The Short Answer: It Depends on the Contract.
In the UK, there is no specific law that says “A boss must give 24 hours notice.” However, they cannot act like dictators. They must follow the contract and “implied terms” of trust.
A Quick Story: Meet Sam
Sam works in retail. His rota is usually published 2 weeks in advance.
On Friday afternoon, his manager changes the rota for Saturday morning without asking him.
Sam has already booked a train ticket to see his parents.
The manager says: “Check the contract, Sam. It says we can vary your hours to meet business needs.”
Sam feels like he has no choice.
The Verdict: The manager is being unreasonable. While the contract does allow changes, changing a confirmed shift with less than 24 hours’ notice when Sam has plans/costs (the train ticket) could be a breach of the “implied term of mutual trust and confidence.” Sam can likely refuse.
The “Flexibility Clause” Loophole
Grab your contract. Look for a sentence like this:
” The Company reserves the right to vary your shift patterns to meet business needs.”
If you signed this, you gave them permission to change your hours. However, this power is not unlimited.
They cannot change it maliciously (to punish you).
They cannot change it impossibly (e.g., telling you at 8:59am to start at 9:00am).
What is “Reasonable Notice”?
Since the law doesn’t give a specific number of hours, “Reasonable” depends on your job.
Zero-Hour Worker: You can refuse any shift change. You have zero obligation.
Full-Time Employee:
12 Hours Notice: Generally accepted as the absolute minimum for most shift work.
24-48 Hours Notice: Considered “Reasonable” / Good Practice.
Less than 12 Hours: Very likely “Unreasonable” unless it is a genuine emergency (like a flood).
Can They Send Me Home Early? (Unpaid)
You turn up for an 8-hour shift. After 2 hours, it’s quiet, and the boss says: “Go home, we don’t need you.” Do they still have to pay you?
If you are on a Salary: YES. They must pay you for the contracted hours, even if there is no work.
If you are Hourly (Zero-Hour): NO. They usually only pay for the hours you actually worked (unless your contract says otherwise).
How to Say “No” (Without Getting Fired)
If your boss keeps messing you around, you need to draw a line. Do not just shout “That’s illegal!” (because it might not be).
Use this template to refuse politely:
“Hi [Manager], I saw the rota change for tomorrow. Unfortunately, I cannot work that new time due to prior commitments made based on the original rota. With such short notice, I am unable to rearrange them. I am happy to work my original shift as planned.”
Why this works:
It is professional.
It highlights the “short notice.”
It offers a solution (working the original shift).
Summary: Be Flexible, But Firm
Workplaces need flexibility, but they don’t own your life.
Check the Contract: Does it say they can change shifts?
Check the Notice: Was it reasonable?
Stand Your Ground: If you have a doctor’s appointment or childcare, “Business Needs” do not override your life.
(Sources: Acas – Changing an employment contract, Citizens Advice – Changes to employment contracts)
This guide is for information purposes only and is not legal advice. Always read your specific employment contract. Consult Acas for disputes.