This guide is about applying for jobs in the UK.

You drafted your cover letter with an AI tool, tidied it up, and then a worry crept in. If you can tell it started with AI, can the employer tell too? Will a checker somewhere flag it and bin your application before a person ever reads it?

It is a fair worry, and it deserves an honest answer rather than a sales pitch. The short version: nobody can prove who or what wrote your letter, the tools that claim to are unreliable, and the thing recruiters actually react to is not the tool you used. It is whether the letter sounds like anyone in particular.

This guide sits alongside our main guide on how to write a cover letter for UK jobs. Read that for the structure. Read this for the part everyone is quietly anxious about.

Do Job Applications Check for AI?

The plain answer is: sometimes, and not in the way most people imagine. A few employers run cover letters through AI-detection software. A few recruiters form a hunch by eye after reading hundreds of letters a week. Many hiring teams do no formal check at all, because they are short on time and a detection score does not tell them whether you can do the job.

So do job applications check for AI as a rule? No. There is no universal scanner sitting between you and the hiring manager that quietly rejects AI-assisted writing. Practices vary by company, by recruiter, and by role.

Here is the part worth holding onto: even where a check happens, it cannot deliver a verdict. The next section explains why. What that means for you is simple. Spend your energy on the letter being unmistakably yours, not on outwitting a tool that, in most applications, is not even running.

What AI Detection Can and Cannot Do

It helps to be clear-eyed about what these tools actually produce. An AI-detection tool reads your text and returns a likelihood, a percentage or a label such as "likely AI". It does not return proof, and it cannot point to a sentence and say a machine wrote that one.

That limitation is widely acknowledged, including by the people who build these tools. Two failure modes matter for you as an applicant:

False positives. Genuine human writing, especially clear, well-structured prose, can be flagged as AI. Plenty of careful writers have been wrongly accused.
False negatives. AI text that a person has edited often slips through unflagged. The more you shape a draft into your own words, the less any detector has to grip.

Because of this, a responsible employer treats a detection score as a weak signal at most, never as grounds to reject on its own. An applicant cannot control whether a given company runs a checker, nor what threshold it uses. Trying to reverse-engineer a tool you cannot see is a losing game.

So the question "how to check if a cover letter is AI generated" has an uncomfortable answer for employers as well as applicants: there is no method that settles it. That uncertainty cuts both ways, and it is exactly why the smarter move is to stop thinking about detection at all.

Why Generic Is the Real Risk, Not AI

Shift the lens for a moment. A recruiter skimming a deep stack of applications is not hunting for AI. They are hunting for a reason to keep reading. The letters that lose them are the ones that could have been sent to any company for any role.

That is the real hazard with an unedited AI draft, and it has nothing to do with detection. Ask a tool for "a cover letter for a marketing role" and it will hand you something fluent, polite, and completely interchangeable. The recruiter has read that letter fifty times this week. They do not need to prove it was AI. They simply move on.

So the bar is not "undetectable". The bar is specific. A letter packed with your own evidence, mirroring this advert's wording, naming this employer for a real reason, reads as yours whether or not a tool helped you write it. As it happens, that same specificity is also what makes any detector least confident, because the text is now anchored in facts only you could supply.

This is why the honest advice is not "avoid AI" but "edit AI into your voice". The two goals, sounding human and convincing a recruiter, turn out to be the same goal.

How to Keep the Letter Yours

If you start a draft with AI, treat the output as raw clay, not a finished pot. Three moves do most of the work of turning a generic draft into a letter only you could have sent.

Own the Opening

First lines are where unedited AI drafts sound most alike, all variations on "I am writing to express my keen interest". Rewrite that sentence from scratch, in words you would actually use, before you touch anything else. The opening is the most-read line in the letter and the one most worth making yours.

Add Your Own Specifics

A tool can write smoothly about achievements it knows nothing about, which means it will reach for vague claims or, worse, invent plausible ones. Replace every generality with something concrete from your own history: a number you hit, a project by name, a tool you actually used, a problem you actually solved. These details are what a recruiter remembers, and they are details no model can supply for you.

The Generic AI Line

"I am a highly motivated professional with a proven track record of delivering results in fast-paced environments." It says nothing a recruiter can check, and it could belong to anyone.

The Same Point, Made Yours

"In my last role I cut invoice-processing time from five days to two by rebuilding the approval workflow in NetSuite." Same paragraph slot, but now it is evidence only you could write.

Cut the AI Tells

AI drafts lean on a recognisable set of habits: stacked adjectives, phrases like "in today's competitive landscape", a tidy three-part list in every paragraph, and a closing that thanks the reader for their time in the most formal way possible. Trim them. Then read the whole letter aloud. Anything you would never say in a real conversation is a line to rewrite. You are not editing to beat a detector. You are editing so the letter sounds like a person the recruiter might want to meet.

Doing this by hand for every application is genuinely tedious, which is why so many people send the unedited draft and blend into the pile. A tool that tailors your cover letter to each specific advert can take the grind out of the first draft, pulling in the role's own wording, so the time you do spend goes on the specifics only you can add. You still decide what the letter says. That judgement is the part that keeps it yours.

Frequently Asked Questions

Do job applications check for AI?

Some employers run AI-detection tools, and some recruiters form a judgement by eye. Neither is reliable enough to prove a letter was AI-written, and most hiring teams do not run a formal check at all. The honest takeaway is that nobody can be certain who or what wrote your letter. What recruiters can spot easily is a letter that says nothing specific about you or the role, whether a human or a tool produced it.

How do you check if a cover letter is AI generated?

There is no method that gives a definitive answer. AI-detection tools return a probability score, not proof, and they are known to flag genuine human writing as AI and to miss edited AI text. That is why careful employers treat any score as a weak signal at most. A recruiter is far more likely to judge a letter on whether it reads as generic or specific than to run it through a checker.

How do you make a cover letter sound less AI generated?

Rewrite the opening line yourself, since first lines are where unedited AI drafts sound most alike. Replace vague claims with your own specifics: a number, a project name, a tool you used. Cut the filler phrases that AI overuses, and read the letter aloud to catch anything you would never actually say. The goal is not to trick a detector. It is to make the letter genuinely yours.

Is it allowed to use AI to write a cover letter?

Most employers have no rule against it, and many now expect it. The risk is not using AI, it is sending an unedited draft that could have been written for any role at any company. Treat the tool as a first draft you then shape into your own voice with your own evidence. Every claim in the final letter must be true, because the interview will test it.

Conclusion: Make It Yours, Not Undetectable

Chasing an undetectable letter is chasing the wrong target. No tool can prove how your letter was written, and no recruiter rejects on a hunch alone. What loses you the read is a letter that sounds like everyone else's.

So use AI for the first draft if it helps, then do the work that matters: own the opening, load it with your own evidence, and cut anything you would never say. For the full structure that evidence sits inside, head back to our guide on how to write a cover letter.