You have the form open. There is a box labeled "Cover Letter (optional)" sitting under the resume upload, and you are trying to decide whether it is worth ninety seconds of your life. Short answer: fill it, with a short letter, in almost every case. The exceptions are narrow enough that you can check for them in about ten seconds, which we will get to.
Fill it, unless one of these applies
Write something in that box unless you meet one of a handful of conditions. You are applying to a high-volume hourly role where the posting itself says applications are reviewed in bulk by a scheduling system, not a person. You are on page four of a graduate program's application and every other field is a structured, scored question with a word cap of forty. Or the form is visibly broken - the box renders as a single line with no scroll, a clear sign nobody on the other end reads it.
Outside of those cases, an empty box costs you nothing in the two seconds it takes to skip past it, and costs you something real the moment a recruiter opens your file next to a candidate who wrote four sentences. More on that below.
What actually happens to that text
The cover letter box is not decoration. In Workday, Greenhouse, Lever, iCIMS and the rest, whatever you type gets saved as a field on your candidate record, the same record that holds your resume, your answers to screening questions, and your contact details. It shows up in the recruiter's view as a preview pane next to your resume, or as a second tab they can click open.
Here is the part people get wrong: for a high-volume role, that tab often does not get opened. A recruiter triaging three hundred applicants for a warehouse shift is not reading cover letters, full stop. But the moment a role gets to a shortlist - anything senior, anything specialized, anything where the recruiter is down to fifteen names instead of three hundred - the letter tab gets clicked. It is one of the first things a hiring manager opens once a recruiter forwards a shortlist, because unlike the resume it is not formatted for keyword scanning, it reads like a person wrote it.
One more thing worth knowing: the letter field is almost never run through the same keyword parser that scores your resume against the job description. ATS platforms build their matching algorithms around structured resume data - work history, skills, dates. The cover letter text sits there as free text for a human to read, not a field the software ranks you on. Do not stuff it with keywords hoping to game a score. Write it for the person who will eventually open the tab.
Why "optional" is not a neutral word
Nothing on an application form is neutral once you have two candidates who are otherwise level. Same years of experience, same tools on the resume, same answers to the screening questions. The recruiter has to break the tie somehow, and an empty letter field next to a filled one is exactly that kind of tiebreaker information, whether or not the form intended it to be.
An empty box does not read as "efficient candidate who respects everyone's time." It reads as "did not bother," especially when the field sits two inches below a resume upload that took the same ninety seconds to attach. Recruiters know the box says optional. They also know that candidates who care enough to get the job usually fill it anyway.
The plain-text box problem
Here is where good letters go to die: pasted into a plain-text field, most formatting turns to garbage. Line breaks from a Word document collapse into one dense paragraph. Curly quotes and em dashes copied from Google Docs render as stray question marks or boxes. Bullet points paste in as literal asterisks or dashes sitting mid-sentence. And a meaningful number of these fields have a hard character limit - 2,000 or 4,000 characters is common - that will silently truncate your closing paragraph mid-word if you paste in something longer.
The fix is boring and it works. Write the letter in a plain text editor first - Notepad, TextEdit in plain text mode, or a blank note app, not Word and not Google Docs. Keep paragraphs short, three or four lines each, since short paragraphs survive a line-break collapse better than long ones. Avoid special characters entirely: straight quotes only, a plain hyphen instead of a dash, no bullet characters. Once you paste it into the form, scroll up and reread the preview before you submit. A thirty-second check catches the truncated sentence or the row of question marks before a recruiter does.
How long: form field versus attached letter
An attached cover letter, the one that lives as its own PDF, can run 300 to 400 words because it is read as a standalone document with its own visual pacing. A form-field letter is read differently: scrolled through in a narrow box, sandwiched between other fields, often on a screen that is not full size. Aim for roughly 120 to 200 words. That is short enough to read in full without scrolling twice, and long enough to say something specific.
A workable skeleton is four sentences. First, name the exact role and one detail that shows you read the actual posting, not a generic version of it. Second, one achievement with a number attached, chosen because it maps directly to something the posting says they need. Third, a sentence that connects your background to something specific about this employer - their market, their product, their growth stage - not a compliment that could apply to any company. Fourth, a short, low-pressure line inviting the conversation. Four sentences, no throat-clearing, no restating your resume.
A worked example
"I am applying for the Customer Success Manager role at Fenwick Analytics, specifically because the posting mentions building out a proactive renewal process rather than a purely reactive one. In my current role at a twenty-person SaaS company, I rebuilt our renewal workflow and cut involuntary churn by eighteen percent over two quarters by flagging usage drops before the renewal date instead of after. Fenwick's move into mid-market accounts looks like the same problem at a bigger scale, and that is the kind of build I want to be doing next. I would welcome a conversation about where the renewal process stands today and where you want it to go."
That is 121 words. It names the company once, correctly, includes one real number, and closes without begging.
Upload, paste, or both
Some forms offer a choice: attach a file or type into the box, pick one. If you get that choice, upload the PDF. A PDF keeps your formatting, your letterhead if you use one, and reads as more deliberate than a plain-text paste. Use the box for the paste version only when there is no upload option.
The trickier case is a form that demands both - a file upload and a filled text box, no way to submit with one blank. When that happens, do not paste your full attached letter into the box verbatim; it will look strange stripped of its formatting and padded with stray characters. Write a shorter, second version for the box, two or three sentences that summarize the pitch, and let the full letter live in the PDF. Redundant, but redundant is fine. A blank field next to a filled upload box is what actually reads as broken.
Can you reuse one letter across forms
Yes, and you should, up to a point. The four-sentence skeleton above is built to be reused: swap the company name, the role title, and the one detail about their business in sentences one and three, keep your achievement sentence mostly as-is since your track record does not change between applications. That is efficient reuse, not laziness.
The line gets crossed when the reuse stops being active editing and becomes copy-paste on autopilot. If sentence three still describes a company's growth stage that does not match the one you are applying to, or sentence one references a job title that is close but not exact, you have crossed it. Before you submit, reread the letter once specifically checking the company name and role title against the job you have open in the other tab. That single check catches the single most damaging mistake on this list.
The traps that actually cost interviews
A handful of mistakes show up over and over in recruiter feedback, and they are all avoidable with one careful read before hitting submit.
- Wrong company name. A letter that mentions a different employer, left over from your last application, is an instant pass for most recruiters regardless of how good the rest of it reads.
- Longer than the resume. A form-field letter that runs past 250 or 300 words starts to read as padding rather than a pitch, especially in a box with no formatting to break it up visually.
- "To Whom It May Concern" on a form that already knows the team. The application system usually shows the hiring manager's name or the department. Opening with a placeholder greeting on a platform that has that information available reads as a letter you did not bother to update.
- A beautiful letter that lives only in the PDF. You spent real effort on the attached document, then left the box blank because you assumed the file covered it. For a shortlist review, that blank box is often what gets opened first, before the attachment gets a click.
When the field is genuinely pointless
Not every cover letter box is worth your ninety seconds. Bulk shift-work applications - retail, warehouse, hospitality roles hiring dozens of people off one posting - are usually screened entirely on availability and structured answers, and the letter field is a leftover from a generic form template nobody customized for that job type. Some graduate and campus recruiting portals score applicants purely on structured question responses fed into a rubric; a free-text letter sits outside that rubric entirely and nobody reads it before the scored questions have already ranked you.
If you cannot tell which kind of form you are looking at, default to writing the short version anyway. Four sentences cost you two minutes. Skipping a field that turns out to matter costs you a shortlist spot you will never know you lost. When you are pulling your work history and achievements together for a form field like this one, having a clean, well-structured base document to draw sentences from - the kind Postulit builds from your LinkedIn profile - makes writing four honest, specific sentences a lot faster than starting from a blank box every time.