Cover letter vs letter of interest: differences and when to send each

What a cover letter is

A cover letter is a one-page document you send alongside your resume when you apply for an advertised position. Its job is to connect your experience directly to the requirements listed in that posting. Every paragraph should reference something the employer actually asked for.

Because it responds to a real opening, a cover letter can be specific: the job title, the hiring manager's name if you can find it, the team, the product, the problem the role is meant to solve. Vague cover letters get ignored because they could have been sent anywhere.

• Sent in response to a posted job ad
• References the exact job title and requisition number if one exists
• Matches your skills to the stated requirements
• Addresses a specific hiring manager or team where possible
• Typically required by the employer as part of the application

What a letter of interest is

A letter of interest, sometimes called a letter of inquiry or prospecting letter, is sent to a company when no specific role has been posted. You are introducing yourself and signaling that you would like to work there if the right opportunity comes up.

Because there is no job description to respond to, a letter of interest has to do more work. It needs to explain who you are, what kind of role you are looking for, and why this particular company is worth your time and theirs. Generic letters of interest are easy to ignore, so the more research you show, the better.

• Sent proactively, not in response to a posting
• Targets a company, not a specific role
• Explains the type of work you do and the value you bring
• Shows genuine knowledge of the company's direction or recent work
• Often sent to a department head or talent team directly, not through an ATS

Key differences side by side

The table below summarises the practical differences. Both documents should be one page, professional in tone, and tailored to the recipient. That is where the similarity ends.

• Trigger: cover letter follows a job ad; letter of interest follows your own research
• Audience: cover letter goes to a hiring manager for a known role; letter of interest often goes to a recruiter, department head, or general inbox
• Specificity: cover letter mirrors the job description; letter of interest mirrors the company's work and culture
• Outcome: cover letter leads to a formal application; letter of interest may lead to a conversation, a referral, or being kept on file
• Tone: cover letter is slightly more formal because a process already exists; letter of interest can be a little warmer because you are starting a relationship

When to send a cover letter

Send a cover letter whenever a job posting exists and the employer asks for one, or whenever the application system has a field for it. In the US, Canada, the UK, and Australia, most corporate roles on platforms like LinkedIn, Seek, or Indeed still expect one, even if they mark it optional. Submitting one when it is optional is almost always worth doing.

The cover letter is also your chance to explain anything the resume cannot, such as a career change, a gap, or why you are relocating. Keep it to three or four short paragraphs: why this role, why you, and what you would do in the first 90 days if you can be specific.

1. Open with the role title and one sentence on why it fits your background
2. Spend one paragraph on your most relevant experience, using numbers where possible
3. Spend one paragraph on why this company specifically, not just the industry
4. Close with a clear next step, such as requesting a call or interview

When to send a letter of interest

A letter of interest makes sense in three situations: you want to work at a company that rarely posts roles publicly, you have a strong contact inside the organisation who suggested you reach out, or you are targeting a niche industry where most hiring happens through networks rather than job boards.

It also works well after a company has gone through a round of layoffs and paused hiring. Reaching out six to twelve weeks later, when things have stabilised, can put you in front of a hiring manager before a role is even posted.

Keep the letter short, around 200 to 300 words. Name a specific team or type of work. Reference something real about the company, a product launch, a published case study, a recent hire you admire. End by asking for a 20-minute call, not a job.

How Break-In Bad handles cover letters for posted roles

When you apply through Break-In Bad, Omar reads the full job posting and writes a tailored cover letter drawn from facts you have already confirmed during your resume build. She does not invent details or pad the letter with filler. Every claim in the letter maps back to something you said.

If a role scores 75 percent or above on your match, Break-In Bad can apply automatically on Greenhouse, Lever, Workday, and other employer sites, attaching the tailored cover letter and sending you a screenshot as proof. For roles between 45 and 74 percent, you review before it goes out. That review step is a good moment to check the cover letter and adjust the tone if the company culture calls for something less formal.

Common mistakes with both documents

The biggest mistake with a cover letter is restating the resume. The reader already has the resume. Use the cover letter to add context, show judgment, and demonstrate that you understand what the role actually requires.

The biggest mistake with a letter of interest is being vague. Saying you are a passionate team player who would love to contribute to a dynamic organisation tells the reader nothing. Name the team, name the problem you could help solve, and name a specific piece of the company's work that you respect.

In both cases, proofread for the company name. Sending a cover letter to Atlassian that mentions Notion, or a letter of interest to a Sydney office that references a Toronto address, ends the conversation immediately.

• Do not summarise your resume; add to it
• Do not use the same letter for more than one company without editing it
• Do not address it 'To Whom It May Concern' if you can find a name
• Do not exceed one page
• Do not forget to update the role title and company name if you adapt a previous letter