Starting from real duties, not a blank page
Writing a job description from nothing usually means either copying somebody else's badly, or spending an hour trying to remember every task a role actually involves. Picking a starting role fills the duties list with genuine, commonly used lines for that kind of work, which can then be edited, removed or added to freely rather than treated as fixed.
More than one role can be combined, which is the common case for a smaller employer where one person covers ground that would be two separate jobs somewhere bigger: a site operative who also drives, or an administrator who also handles customer calls.
A job description is not the same document the law requires
The Employment Rights Act 1996 requires a written statement of employment particulars, and it has to include a job title or a brief description of work among a longer list of specific items. That is a separate legal minimum from a full job description, and having one does not automatically satisfy the other. Most employers keep the two apart on purpose: the written statement is a compact statutory document and the job description is the longer, more detailed one that changes more often as a role develops.
For the same reason, most employers keep the job description non-contractual, often with a closing line along the lines of "and any other reasonable duties", so the role can shift a little without a formal variation to the contract every time a task changes. Whether the duties on this page are contractual in a given case depends on what the actual employment contract says, not on this document alone.
Essential criteria have to earn the word "essential"
A person specification splits requirements into essential and desirable for a reason beyond tidiness. Under the Equality Act 2010, a requirement that indirectly disadvantages people sharing a protected characteristic can amount to indirect discrimination unless it is objectively justified by what the job genuinely needs. A flat number of years' experience is the requirement that catches employers out most often: it can disadvantage younger candidates without necessarily being the best measure of whether somebody can do the job.
Keeping the essential list short and tied to the role, and moving anything merely useful into desirable, is both fairer and easier to defend if a recruitment decision is ever questioned.
A requirement can exclude people you did not mean to exclude
This is where a job description does its real damage, and it is rarely deliberate. A criterion that looks neutral can still disadvantage a group protected by law, and if it does, it has to be justifiable as a proportionate way of meeting a genuine need. "Must have five years continuous experience" excludes people who took time out to raise children. "Must hold a full driving licence" excludes some disabled applicants where the role does not actually require driving. "Excellent written English" is legitimate for a copywriter and a barrier for a welder.
The test to apply to every line is simple: could somebody do this job well without it? If the answer is yes, it is desirable rather than essential, and moving it is free. Doing that at the writing stage costs nothing. Doing it after a complaint costs a great deal, and the document you wrote is the evidence either way.
Salary bands and grading belong to a pay structure
Salary bands, job grading against a pay structure, and how a role maps onto an organisation chart are all outside this tool. It builds the duties and the person specification; pay and structure are decisions that belong to whoever is running the recruitment.
Common questions
Is a job description a legal requirement?
No, not on its own. The legal minimum is the written statement of employment particulars under the Employment Rights Act 1996, which must include a job title or a brief description of work among other things. A full job description supports that but is a separate document, and there is no standalone legal duty to produce one.
Does listing duties here make them contractual?
Not automatically. Most employers keep a job description as guidance rather than a contract term, usually with an "and any other reasonable duties" line, so the role can flex slightly without a formal change to the employment contract every time a task shifts. Whether this document is contractual depends on what the actual contract says about it.
Can I require a fixed number of years of experience?
Be careful with it. A requirement can be indirect discrimination under the Equality Act 2010 if it disadvantages people sharing a protected characteristic and cannot be objectively justified by the genuine needs of the role. A long, arbitrary experience requirement is one of the more common ways this catches employers out.
Is this the same thing as a person specification?
No, and keeping them apart is what stops a job description turning into a wish list. A job description says what the ROLE does: the duties, who it reports to, where it sits. A person specification says what the POSTHOLDER needs: the skills, the experience, the qualifications. Most recruitment problems come from mixing the two, because a duty written as a requirement quietly becomes a barrier nobody intended.
What does "and any other duties as required" actually do?
Less than people think, and more than they want. It is there to stop an employee refusing a reasonable request that was not listed, and courts read it narrowly: it covers duties of a similar nature and level, not a different job. It will not let you move somebody from an office role onto a delivery round. Where a role genuinely changes, the honest route is a new description and a conversation, not a catch-all sentence written two years earlier.
What is the difference between essential and desirable criteria?
Essential criteria are the minimum a candidate must have to do the job; desirable ones are useful extras that are not strictly required. Keeping the two separate, and keeping the essential list to what is essential, makes shortlisting fairer and easier to defend if a decision is ever questioned.