Key takeaways
- A cover letter does not compete with your CV: it answers the question your CV leaves open. If your CV leaves none, you can skip it.
- It changes the outcome in five cases: a change of sector, a career gap, a move to another city or country, a requirement you only partly meet and an internal referral.
- If the job ad asks for one, always send it. If the field is optional and you are unsure, three specific sentences beat an empty box.
- One paragraph does the work: the fact, the evidence with a number and what you would do in the role. No apologies.
What the data says, and what it doesn't
Every few months someone declares the cover letter dead. The few studies with a real method say otherwise. The most quoted is a ResumeGo experiment that sent 7,287 fictitious applications to real job ads in the United States, with and without a letter, and counted the callbacks. Alongside it sits a Resume Genius survey of 625 US hiring managers.
Read them carefully. This is US data from jobs posted on large boards; we have not found a comparable UK or European study we could verify. And what they measure is not letter versus no letter, but a tailored letter versus nothing at all. A generic letter is not the same thing, and hardly anyone rates the two equally.
more callbacks for applications with a letter tailored to the job than for those with no letter, in an experiment with 7,287 applications.
Source: ResumeGo, "Cover Letters: Just How Important Are They?", experiment with 7,287 applications in the US (2019-2020)of the hiring professionals surveyed value a tailored letter significantly more than a generic one.
Source: ResumeGo, "Cover Letters: Just How Important Are They?", experiment with 7,287 applications in the US (2019-2020)of hiring managers at companies that do not require a cover letter say they read it anyway, always or frequently.
Source: Resume Genius, survey of 625 US hiring managers (2023)How recruiters really use it
Almost nobody reads the letter first. The usual order is different: the CV decides whether the application goes forward, and the letter gets opened when the CV raises a doubt or when two candidates are neck and neck. That is why a brilliant letter cannot rescue a CV that does not answer the ad, and a mediocre letter rarely sinks a CV that does.
Where it carries most weight is with applications that do not fit at first glance: someone coming from another sector, someone who has been out of work for a year or someone who lives in another city. The CV raises a question there, and if nothing answers it, the recruiter answers it alone, usually with the least favourable assumption.
There is a third use few guides mention: the letter gets read again before the interview. What you wrote becomes questions. So every sentence has to be something you can defend out loud.
When to write one and when not to
Not every application deserves the same effort. This is the table we use at Cernoria to decide, depending on the channel and on what your CV already says:
| Situation | Letter? | Why |
|---|---|---|
| The job ad asks for one | Yes, always | Leaving it out means not following an instruction, and it is the first thing they notice. |
| Large job board, optional field, hundreds of applicants | Short or none | It is rarely opened. If your CV already answers the ad, your time is better spent tailoring it. |
| Application by email to a named person | Yes, in the body of the email | The email is the letter: it is the first thing they read. |
| Change of sector or function | Yes | The CV shows where you come from; the letter explains why the move makes sense. |
| Gap in your career | Yes, one sentence | A gap with no context gets filled with the worst assumption. |
| Relocating or applying from abroad | Yes | The recruiter wonders about your start date, right to work and commitment. One sentence settles it. |
| Someone at the company referred you | Yes, short | Naming the person and the reason gets your application read sooner. |
| High-volume role with an automated process | Not needed | It is decided on availability and requirements. That time is better spent on another application. |
The five cases where it changes the outcome
In these cases the CV, however well written, cannot tell the whole story. The letter is the only place in the application with room for context:
- A change of sector or function. This is not about asking for a chance, but about showing which part of what you already do is the same job under another name.
- A career gap. One neutral sentence in the past tense ("In 2025 I cared for a family member and I have been available since January") closes the topic. More than one sentence reopens it.
- Relocation. If the job is in Manchester and your CV says Glasgow, say when you will be there and that you have the right to work. Without that, plenty of applications are dropped for logistics, not for the profile.
- A requirement you only partly meet. Do not say what you lack: show the closest thing you have done, with a figure, and let the reader draw the conclusion.
- An internal referral. Name the person in the first line and say how you know them. It is the most powerful sentence in the whole letter.
A cover letter does not compete with your CV: it answers the one question your CV leaves open. If your CV leaves none, the best letter is the one you do not write.
How to decide in 30 seconds
Before you open a blank document, answer these four questions in order. The first "yes" decides, and also tells you what the letter needs to be about:
- Does the job ad ask for one?
If it does, write it, even if it is short. Decision made.
- Does your CV leave a question open?
A change of sector, a gap, another city or a requirement you only half meet. If so, write it and give the middle paragraph to that question.
- Is it going to a specific person?
A direct email, a referral or a small company where the reader is the decision maker. If so, keep it short and specific.
- None of the above?
Do not write it. Spend that time tailoring your CV to the ad or on one more application.
The paragraph that matters
Once you have decided to write it, the whole letter does not need to be excellent. One paragraph does: the one that answers the question that made you write it. It has three parts, always in this order: the fact (what is changing or needs explaining), the evidence (something you did, with a number) and the forward look (what you would do with it in this role).
What it never contains is an apology. "Although I have no experience in..." points the reader to a reason to reject you that they may not have spotted, and wastes the best line in the letter. The full structure and a sample letter are on our cover letter page; here is just that paragraph, before and after.
Case: Liam Example, eight years as a secondary school teacher, applying for an in-house learning and development role at a logistics company.
Before: "Although I have no corporate experience, I believe my teaching skills could be useful to your training team and I am highly motivated to learn."
After: "For eight years I have designed and delivered training for groups of thirty. For the last two I led my school's move to digital: I trained 40 colleagues and in one year we went from 5 to 32 teachers using the online platform. It is the job your ad describes, with adults who work at a different pace, and in my first months I would start the same way: find out who already uses the tools and who does not, and train first the people who bring the others along."
What AI has changed
Writing a decent cover letter now costs nothing, which is exactly why a decent cover letter no longer sets anyone apart. Recruiters receive stacks of letters that sound the same: enthusiasm, team player, eager to learn. What cannot be generated without you is the specifics: the number, the name of the project, the real reason it is that company and not another.
Using AI to structure and polish your letter makes sense, as long as the material comes from your own experience. A letter that mentions an achievement you never had falls apart at the first interview question, and takes everything else with it.
Frequently asked questions
Do employers still read cover letters?
Many do, especially when the CV raises a doubt or two candidates are close. In a Resume Genius survey of 625 US hiring managers, 73% of those who do not require one said they read it anyway, always or frequently.
Should I send a cover letter if the job ad does not ask for one?
Only if your CV leaves a question open (a change of sector, a gap, a relocation, a requirement you only half meet) or the application is going to a specific person. Otherwise your time is better spent tailoring the CV.
How do I explain a career gap in a cover letter?
With one neutral sentence in the past tense saying what you did and since when you have been available. No justifying and no detail: one sentence closes the topic, a paragraph reopens it.
What do I write if I do not meet every requirement?
Do not name what you lack. Show the closest thing you have done, with a concrete figure, and what you would do in the role. The reader will draw the conclusion.
Is a cover letter written with AI any good?
Yes, if the content comes from your real experience and you check it before sending. A letter generated from the job ad alone sounds like all the others and adds nothing your CV does not already say.
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