The Short Answer
Yes, in most cases. If the job advert asks for a cover letter, it's required. If there's anywhere to add one (an upload field, an email application, a "covering note" box), send a short, tailored one. The National Careers Service advises always including a cover letter when you apply with a CV. The key word is tailored: a generic letter that could go to any employer adds little, and a letter with the wrong company name does real harm.
You can usually skip it when the employer uses an application form with its own questions, or when there's simply nowhere to put one.
When a Cover Letter Matters Most
- The advert asks for one. If the listing says "please send your CV and a cover letter" and you only send a CV, you've failed the first test.
- Small and medium employers. At a small firm, the person reading your application is often the person you'll work for. A good letter is your first conversation with them.
- Competitive roles. When several candidates have similar CVs, the letter is where you show you understand this particular job.
- Career changers. Your CV shows what you've done. Your cover letter explains why you're moving and why your experience transfers. Our career change CV guide covers the CV side.
- Gaps or anything that needs context. One calm sentence about a career break or a relocation stops the reader guessing. See how to explain gaps in your CV for wording.
- Speculative applications. If you're writing to an employer that hasn't advertised a job, the letter is the application. The CV is the supporting evidence.
- Moving to a new area. If your CV shows an address in another city, a line saying you're relocating (and when) answers an obvious question.
When You Can Skip It (or Keep It Very Short)
- Application forms with their own questions. Many public sector employers, including the NHS and the Civil Service, use online forms with a supporting statement instead of a cover letter. Put your effort into that statement. Our NHS CV guide explains how NHS supporting statements work.
- No upload field. If the online system only takes a CV, don't squeeze a letter into the CV file.
- Some recruitment agency submissions. Agencies usually present you to their client with their own summary, so a long letter often isn't passed on. A short, specific email to the recruiter is still worth sending.
- Quick-apply buttons. One-click applications on job boards rarely have room for a letter. For roles you really want, it's often worth applying on the employer's own site instead, where you can add one.
What "Cover Letter Optional" Really Means
When a form says a cover letter is optional, treat it as an opportunity rather than permission to skip it. Optional means some applicants won't bother. A short, specific letter (even 150 words) is an easy way to stand out from the people who left the box empty, especially for jobs you genuinely want.
How Long Should a Cover Letter Be?
Less than one page. The National Careers Service describes a cover letter as usually three to five paragraphs long. In practice, around 250 to 400 words works for most jobs, and less for part-time or entry-level roles. If yours is spilling onto a second page, it's repeating your CV.
What a Good Cover Letter Looks Like
Forget the long, formal essay. A modern UK cover letter has four parts:
- Opening: the job you're applying for (and the reference number, if there is one) and your headline reason for being a strong fit.
- Evidence: two or three of the most important requirements in the advert, each matched with something you've done. Pick achievements; don't retell your whole CV.
- Why them: something specific about the employer, team or role that genuinely appeals to you. This is the part generic letters always miss.
- Close: thank them, say you'd welcome an interview, and add anything practical such as your notice period or availability.
Address it to a named person if you can find one (the advert, the company website or LinkedIn usually help). Sign off "Yours sincerely" when you've used their name, or "Yours faithfully" after "Dear Sir or Madam". For full letters you can adapt, see our UK cover letter examples, which include a part-time job, an apprenticeship, a graduate role, a career change and a returner.
Cover Letters by Email
When you apply by email, the email itself is your cover letter. Keep it shorter than an attached letter, use a clear subject line ("Application: Marketing Executive, ref ME-204, Jordan Ellis"), and attach your CV as a PDF with your name in the file name. Don't send a blank email with two attachments: many readers won't open the second one.
Does Anyone Actually Read Them?
Honestly, it varies. Some recruiters read every letter. Some only read them for candidates who are already on the shortlist. Hiring managers at small businesses often read them closely, because they're choosing someone to work alongside. You can't know which kind of reader you'll get, which is why the best approach is a letter that's short enough to cost a busy reader nothing, and specific enough to help you if it's read.
Common Cover Letter Mistakes
- The wrong company name or job title, left over from the last application
- Opening with "My name is..." or "I am writing to apply for..." with nothing after it
- Repeating the CV line by line
- Talking only about what you want from the job rather than what you'll bring
- Claims with no evidence ("I am a natural leader")
- Going over one page
- Typos. Read it out loud before you send it
Should You Use AI to Write It?
AI can save a lot of time on the first draft, and writing a tailored letter for every application used to take a long time. Mojo's cover letter builder drafts a letter from your CV and the job description, so you start with a structure tailored to the role. Treat it as a first draft: add your best evidence, cut anything that sounds generic, and make sure it sounds like you. Readers notice letters full of stock phrases, whoever wrote them. The builder is one of the AI tools in your free CV Mojo account, which comes with 3 AI tokens; the Job-ready pass or Pro gives unlimited use.
Quick Decision Checklist
- Advert asks for a cover letter: send one
- Upload field or email application: send a short, tailored one
- Application form with a supporting statement: put the effort into the statement instead
- Agency application: a brief, specific note to the recruiter
- Career change, gap or relocation to explain: definitely send one
- Speculative approach: the letter is the application
- No way to add one: skip it and make the CV do the work
The Bottom Line
A short, tailored cover letter is still one of the most useful things you can add to an application. Many candidates skip it or send something generic, which makes it easier for yours to stand out. And because the letter only works if the CV behind it is strong, check your CV free before you apply: you'll get a CV Score out of 100 for the role and the fixes to make first.