Do you legally need a job description? A UK employer's guide for 2026
A client rang me last year about a new starter who was not working out. Three months in, wrong fit, getting worse. The manager wanted to let them go and assumed that because they were well under two years’ service it would be straightforward. My first question. What does their job description say they were supposed to be doing? There was a long pause. The job description was a generic one lifted from the previous person in the role and nobody had looked at it since. We had nothing solid to measure the person against. This mattered because the performance challenges were linked to a disability.
That phone call is about to get a lot more common because the rules on how quickly employees gain protection are changing. So here is the short answer to the question most employers ask first. No, you are not legally required to have a job description in the UK. But running a business without good ones is about to become much riskier and the job description is one of the most important documents you hold. It is the foundation of recruitment, the reference point for managing performance and the first piece of evidence anyone reaches for when something goes wrong.
This guide covers what the law actually requires, what a good job description includes, whether you can change one and how the Employment Rights Act 2025 changes everything. Job descriptions are crucial for employers and HR teams, not just job hunters and creating job adverts.
Do you legally need a job description?
No. There is no law in the UK that requires you to give an employee a job description. You are required to give every employee a written statement of the main terms of their employment, including their job title or a brief description of the work, on or before their first day. That is not the same as a full job description and the brief version is all the law demands.
The absence of a legal duty is not a reason to skip it. A job description is the document that defines what you need from a role, helps you recruit the right person and gives you something concrete to measure performance against. Without one you are managing on memory and assumption and assumption is exactly what falls apart when you are defending a decision. The question is not really whether you are obliged to have one. It is whether you can afford not to.
What is a job description for?
A job description sets out what a role is. The tasks, the responsibilities, the behaviours, where the role sits in the structure and the contribution it makes to the business. It does two jobs and most organisations only focus on the first one.
The first job is recruitment. The job description helps you work out what you actually need before you advertise and helps the right candidates recognise themselves in the role. The second job is performance management. Once someone is in post, the job description becomes the benchmark for whether they are doing what was expected. Most employers write the job description for the recruitment stage and then never open it again, which means that when a performance problem arises they are measuring the person against a document that no longer reflects the job or against nothing at all. The fix is to treat the job description as a living document you actually use, not a recruitment formality you file and forget. The job description helps set the expectations, a good one guides the onboarding process and training periods to help ensure the individual gets to the performance you need.
How does the Employment Rights Act 2025 change things?
The Employment Rights Act 2025 makes the job description more important than it has ever been because it shortens the time you have to get employment decisions right. From 1 January 2027 the qualifying period for ordinary unfair dismissal drops from two years to six months. The cap on unfair dismissal compensation is removed on the same date.
The change does not only affect people you hire in future. It applies to your existing staff. Anyone who already has six months’ service on 1 January 2027 gains unfair dismissal protection immediately, which in practice means anyone hired up to the end of June 2026 is covered immediately from 1st January 2027. Everyone hired after that gains protection as soon as they reach six months. The two-year runway employers have relied on to address a bad hire is gone.
What does that have to do with the job description? Everything. If you need to address underperformance in the first few months, you measure the employee against the role. If you cannot point to a clear, current, specific job description that sets out what was expected, you have nothing to measure against and nothing to evidence a fair process with. Recruitment and early performance management stop being HR admin and become risk control. The job description is the document the whole thing rests on. You do not need to panic about this but you do need your job descriptions to be in good order well before the deadline and the time to sort that is now while it is calm rather than later when there is a problem on your desk.
What should be included in a job description?
A good job description covers six things. The role title and where it sits in the structure. The purpose of the role and the contribution it makes. The key tasks and responsibilities, grouped sensibly. The behaviours the role genuinely requires. The skills, experience and qualifications that are actually needed. And the working arrangements, including hours, location and any genuine inherent requirements.
The tasks are the easy part because they can be defined and measured. The behaviours are where it gets harder and where most job descriptions go vague. For management roles especially, I see the entire job of managing people compressed into a single line “manage the team”. That is not a description of a job, it is a description of having a team. How does the manager develop people, handle performance, communicate up and down, make decisions? Spell it out because that is what you will hold them to.
The behaviours you list must match what you actually reward. A common failure is listing “attention to detail” almost by reflex then measuring the person on speed and output. The employee who genuinely pays attention to detail, exactly as the job description asked, gets performance managed for being too slow. The document and the reality are pulling in opposite directions and the person is caught in the middle. Before you put a behaviour in, check that it is genuinely what good looks like in that role. If you measure speed, say speed. If you measure accuracy, say accuracy. If you really need both then be honest about how they balance because for most people those two trade off against each other. This is not pedantry. It is the difference between a job description that protects you and one that sets people up to fail.
How is a job description different from a job advert?
The job description is the internal foundation document that defines the role. The job advert is the external marketing document that sells it. You write the job description first because it tells you what the role actually is and the advert then draws the right person in. The advert is shorter, sharper and written to attract. The job description is fuller and written to be accurate.
A lot of organisations do this the wrong way round. They write the advert first and back-fit a job description from it, which produces job descriptions that read like marketing and adverts that read like compliance documents. If your applications are coming from the wrong people, the language in both is usually the first place to look. There is more on getting the advert right in my guide on why your job adverts are putting people off.
Are job descriptions and neurodiversity connected?
Yes and closely. The way a job description is written has a direct effect on whether neurodivergent people can see themselves in a role, apply for it and then succeed in it. This is the area where I do most of my work and where the biggest, most avoidable mistakes get made.
Vague, behaviour-heavy job descriptions disproportionately disadvantage neurodivergent candidates. A phrase like “must be a great communicator and team player” gives a neurotypical applicant enough to guess at, while a neurodivergent applicant who reads it literally often cannot tell whether they can do the role and rules themselves out of a job they would be excellent at. The same problem runs through “essential” criteria that are really just preferences. Every “must have five years’ experience” or “must thrive in a fast-paced environment” is a filter and a lot of those filters screen out capable people for no good reason. The job description is also the foundation document for reasonable adjustments because you cannot work out what adjustments a role needs without an honest description of what the role actually demands.
This matters enough and is specific enough, that I have written a separate guide on inclusive job descriptions for neurodivergent candidates. If recruitment and retention of neurodivergent talent is on your radar, start there. The short version is that the things that make a job description work for neurodivergent people, clarity, honesty and specificity, make it work better for everyone.
Can an employer change a job description?
Yes, in most cases you can and you should keep them current as roles evolve. As long as the change is reasonable for the type of work the person does and does not fundamentally alter the contract, such as status, pay, hours or location, updating a job description is a reasonable management instruction. The strong recommendation is always to discuss the change with the person doing the job and reach agreement because consensus protects the working relationship in a way that imposition never does. If your employment contracts include a sensible flexibility clause, that gives you firmer ground for minor changes, though it does not remove the need to act reasonably.
Should a job description be part of the contract?
No. Keep the job description and the contract of employment separate. The job description describes the role, which will and should change over time. The contract is the legal agreement, which should only change through proper process. If you embed the full job description into the contract you turn every routine update into a contractual variation, which is exactly the position you do not want to be in. Reference the job description in the contract as a supporting document by all means but do not bolt it in.
This matters more under the Employment Rights Act 2025, which makes dismissal and re-engagement, the “fire and rehire” route, automatically unfair in most circumstances from January 2027. You want the freedom to keep job descriptions up to date without that counting as a change to terms. For more on getting this boundary right see my guide to employment contracts.
How do you write a good job description?
Start by understanding what the role actually is rather than what you assume it is. If someone is already doing the job, talk to them and if several people do the same job, talk to more than one of them. Talk to the line manager and to the people who work alongside the role. You will often find that everyone describes it slightly differently and the act of reconciling those views is where the real clarity comes from. Draft it then send it back to the current post-holder to sanity-check against reality then agree and finalise.
For a brand new role the focus shifts to what the business needs the role to achieve, which is harder to pin down than describing a job that already exists. Expect to revisit and refine it over the first year as the role takes shape. Whatever the role, there is no single template that fits everything and the structure should follow what genuinely matters about the job rather than a fixed form. To get you started I have two templates you can adapt:
Getting your job descriptions in shape for 2026
Job descriptions sit where recruitment, performance management, legal risk and inclusion all meet. They are the document most organisations underinvest in and the one that causes the most expensive problems when it is wrong. With the Employment Rights Act 2025 shortening the time you have to get early employment decisions right and with the change reaching your existing staff and not just new hires, getting them in order is worth doing now rather than when a problem forces it.
This guide covers the principles but every business and every role is different, so always take advice on your own circumstances.