How to Write an Effective Complaint Letter to Your Boss About a Coworker

Dealing with a difficult coworker is never easy. Their disruptive or inappropriate behavior can negatively impact the whole team’s morale and productivity. While the ideal solution is to resolve issues directly with the problematic coworker, that’s not always possible. When one-on-one conversations fail to improve the situation, it may be necessary to take things up with your boss or human resources department. A well-written complaint letter can help bring their attention to the matter in a professional manner.

Before Drafting the Letter

Before sitting down to write your complaint letter, there are a few things you should do:

• Try to resolve the conflict on your own first Have an in-person discussion with your coworker to share your concerns. Oftentimes problems arise due to miscommunication or misunderstanding Give them a chance to share their perspective and try to find some common ground.

• Document all incidents thoroughly. Keep a detailed log of every inappropriate interaction or incident of unacceptable behavior Note the date, time, location, what was said/done, and any witnesses Specific facts will help support your claims.

• Review company policies. Check your employee handbook or code of conduct to see if your coworker’s actions clearly violate any rules. Reference the relevant policies in your letter.

• Consult HR if needed. You may want to have an informal discussion with your HR rep before submitting a formal written complaint. They can advise if you have sufficient grounds to move forward.

• Be prompt. Don’t let problems drag on for too long before informing your boss or HR. The sooner they are aware, the sooner action can be taken.

How to Write the Letter

When drafting your formal complaint letter, follow these tips:

Use a professional letter format

• Include the date at the top of the letter.
• Use a standard business letter template.
• Add the recipient’s name, job title, and company address.
• Use a formal salutation like “Dear Mr./Ms. [Name]”.

State the purpose clearly

• Open the letter by clearly stating your reason for writing. For example: “I am writing to formally complain about the behavior of my coworker, [name], which I feel has created a hostile work environment.”

Provide specific examples

• Outline the offending behaviors and reference any supporting documents.
• Use exact quotes, dates, times, locations, and names of witnesses if possible.
• Make sure to contextually frame all examples.

Describe how the behavior affects you and your work

• Explain how your coworker’s conduct interferes with your productivity.
• Note if you feel anxious, threatened, or uncomfortable.
• Mention if other team members have raised similar concerns.

Explain how you’ve tried to resolve the issue directly

• List any previous attempts to discuss the problem one-on-one.
• Share what steps you’ve already taken to mitigate the situation.

Suggest potential solutions

• Recommend HR mediate a discussion between both parties.
• Propose implementing a performance improvement plan.
• Ask that disciplinary action be taken if behavior continues.

Maintain a professional tone

• Stick to the facts without getting personal or emotional.
• Avoid aggressive or threatening language.
• Focus on resolving the conflict constructively.

Request a formal follow-up

• Ask for written confirmation that the complaint was received.
• Set a timeline for when you can expect follow-up steps or decisions.
• Offer to provide additional information if needed.

Proofread before sending

• Double check for spelling, grammar, and formatting issues.
• Make sure tone and content are professional.
• Consider having a trusted colleague review the letter.

Following Up After Sending Your Complaint

Once you’ve submitted your written complaint be sure to follow up appropriately

• Keep a copy for your own records. This documents that you notified management of the ongoing issues with your coworker.

• Adhere to next steps provided by HR/management. Cooperate fully with any investigation process or disciplinary actions.

• Maintain professionalism. You want to be seen as cooperative, calm and focused on resolving the conflict.

• Avoid further conflicts. Prevent the situation from escalating by limiting contact with the problematic coworker.

• Continue documenting. If the issues persist, keep detailed records of any further incidents after management has been informed. This creates a paper trail.

• Follow up if needed. If several weeks go by without any resolution, check in with your boss/HR contact again in writing. Inquire about status and next steps.

• Consult a manager. If the situation remains unresolved and is seriously impacting your work, you may need guidance on next steps from a manager or mentor.

• Contact an employment lawyer. As a last resort, if your employer does nothing to address unlawful harassment or retaliation against you, consider seeking legal counsel.

Writing a professional, detailed complaint letter is an important way to document workplace conflicts and request formal intervention from management. With some preparation and planning, your letter can help lead to a fair resolution. Always put the facts in writing to protect yourself, raise concerns constructively, and work to eliminate the negative behaviors hampering your and your team’s performance.