What an ATS is, and what it really does with your CV

What an ATS is

An applicant tracking system is the database behind a careers page. When an employer opens a role, the ATS publishes the listing, takes in every application, and gives the hiring team one place to read them, leave notes, book interviews and send the replies. Greenhouse and Workday are two you'll meet often in UK tech: if an Apply button has ever sent you to an address with greenhouse.io or myworkdayjobs.com in it, you have already used one. GradGrid reads its listings straight from systems like these.

Among large employers an ATS is close to universal. A 2025 check of the Fortune 500's careers pages found an ATS behind 492 of them.

Why employers use one

Volume. The Institute of Student Employers' 2026 survey of 155 UK employers counted 141 applications for every graduate role, and 172 in London. Between them those employers received more than 1.7 million applications in a single cycle. The figure has held at about 140 for three years, the highest since the ISE began counting in 1991.

Nobody reads that many CVs out of an inbox. An ATS exists so that a small team can sort a very large pile, and everything it does to your CV follows from that.

What happens after you press Apply

1. Your CV is read into fields. The system turns your file into text and tries to work out which parts are your name, your employers, your job titles, your dates and your degree. This is called parsing. It is why a form sometimes fills itself in from your upload, and why it sometimes does so wrongly. One large vendor's own guide says its parser doesn't fill in skills or languages at all, so those are yours to type.
2. Your answers are checked. Most forms ask a few yes-or-no questions: do you have the right to work in the UK, will you need sponsorship, do you hold the degree. An employer can set a rule that turns down anyone who gives a particular answer. Another vendor's documentation describes its auto-reject in exactly those terms: it acts on answers to application questions, not on the CV. This is the one step where software regularly says no by itself.
3. You join a queue. Your application lands in a list in front of a recruiter, with your CV shown exactly as you sent it. By that vendor's own account, the list is usually worked through in the order the applications arrived.
4. On a busy role, the recruiter narrows the list first. Faced with hundreds of applicants, they filter and search before they read. In a 2025 survey of 384 recruiters, 76% said they start by filtering on skills, 60% filter on education and 55% on job title. A CV that never uses the listing's word for a skill may simply not come back.
5. Some systems add a score. That is a number or grade for how closely a CV matches the role, and practice varies: some vendors say their software doesn't score or rank candidates at all, while others sell matching as an add-on. In interviews with 25 recruiters in 2025, 11 had a score in front of them, and nine of those used it only as a guide to what to read first. In the UK, 16% of the ISE's employers use AI somewhere in recruitment and another 29% plan to within a year.
6. A person decides. Whatever the software did, the yes or no comes from someone reading your CV, and reading it fast. An eye-tracking study of recruiters put the first look at 7.4 seconds, and the CVs that came through it best had clear headings and bold job titles.

The myth: “75% of CVs are rejected by a robot”

You will see this number everywhere. It traces back to Preptel, a company that sold CV optimisation and went out of business in 2013, and no study was ever published behind it.

What evidence there is points the other way. Of the 25 recruiters in the interviews above, 23 said their system rejects nothing automatically on a CV's format or content. The other two had set a match threshold themselves. That is a small sample, gathered by a company that sells CV tools, but it agrees with what the vendors' own manuals describe.

What is true: you can be missed

None of this makes the system harmless. In Harvard Business School and Accenture's 2021 study of hiring, 88% of employers agreed that qualified, high-skilled candidates were being screened out because they didn't match the exact criteria in the job description.

The mechanism is less a robot rejecting you than a filter nobody looks behind. One vendor says as much: on a busy role, an application that falls outside the recruiter's filter may never be opened. To the employer, an unread CV and a rejected one are different things. To you they are the same silence.

So there are four ways to lose at this stage. In the order they happen:

• a CV the parser has scrambled,
• a screening answer that rules you out,
• wording that keeps you out of a filter or a search,
• a page a busy person can't make sense of in seven seconds.

All four are in your hands.

How to write for it

Taking those in the same order:

• Keep the layout plain. One column, ordinary headings (Education, Experience, Projects, Skills), and nothing that matters in a text box, an image, a header or a footer. Vendors don't publish their parsers' rules, so this is practitioners' experience, not documentation. But the eye-tracking study found that people read plain, clearly headed pages best too, so it costs you nothing.
• Send real text. A PDF exported from a word processor, or a .docx. If you can't select the words in your PDF, the parser can't read them either.
• Check what the form filled in. Correct anything the parser got wrong, and type your skills in where it asks for them.
• Take care over the screening questions. They are the automatic part, so read each one twice before you answer.
• Use the listing's words. If it says PostgreSQL, write PostgreSQL, not “SQL databases”. Give an acronym and its long form once: “Amazon Web Services (AWS)”. There is more on this in seven small changes that fit your CV to the job.
• Apply early. Thirteen of the 25 recruiters interviewed review in order of arrival, and the ISE reports employers closing campaigns early when the numbers get too high.
• Skip the hidden keywords. White text and a pasted-in job description do nothing for you, because the recruiter sees the CV exactly as you sent it.

Your rights in the UK

UK law puts conditions on leaving a decision like this to software alone. Under the Data (Use and Access) Act 2025, when a significant decision about you is taken with no meaningful human involvement, you must be told about it, you can put your side, you can ask for a person to look again, and you can contest the result. The Information Commissioner's Office gives online recruitment with no human involved as an example of a decision with that kind of weight.

If a rejection arrives minutes after you applied and nothing in your answers explains it, you are entitled to ask how it was made.

The bottom line

An ATS is a filing cabinet with a search box and a few rules the employer wrote. Write a CV that a parser can read, a search can find and a person can follow in seven seconds, and you have done what there is to do.