A warning letter is a disciplinary action taken by an organization for disorderly conduct, poor performance or breaking office rules and regulations.
If there is an infraction by an employee, then the first step taken by a company is to give a verbal warning. But a repetition of the same offence can result in a written reprimand that goes in the official profile file of an employee and can become a hurdle in yearly appraisals and such.
The Human Resource departments of companies have a formal process in place to record misconduct. The steps involved are an oral warning and if the behavior persists, then an official written warning is served to the employee and due record and documentation done of the same.

Every company seeks a better working environment within an acceptable work culture.
Here are a few examples of warning letters to help out newbie companies who are new to the process.
TEMPLATE 1
Date:
Name/Address:
Subject: Re: Warning for unacceptable conduct in a public forum
This letter serves as an official warning to you for the incident that happened on <Date of Incident>. It was brought to our notice that your behavior at the Sales Conference held at (place) was found to be crossing the boundaries of proper social conduct. (Describe briefly the incident). This kind of behavior is unacceptable in a professional setting and reflects badly on the company you represented in this forum.
Your behavior also is against Company Policy listed under section 121.
Since you have been found in violation of this rule, please note you are on a warning period from date… to date… Your office conduct will be monitored during this period. Any re-occurrence of such behavior will ensure termination without prior notice.
We expect to see positive outcomes from this discussion.
Sincerely
Your name
Company name
Signature
TEMPLATE 2
To: [employee name]
Date:
Subject: Disciplinary warning action for irregular attendance
Dear XYZ,
This letter is to bring to your attention that your irregular attendance in the office for the past few months. It has been observed that you are taking leave without prior notice and even coming in late and leaving early.
Additionally, you are not meeting your work deadlines, and the quality of your work is also not up to par. You have already been warned about this verbally, but we have notices no improvement in your attendance.
This formal letter of warning is a request to strictly adhere to the work timings and commitments as per company policy. After this, we will be forced to take stronger action.
You are welcome to discuss and personal difficulties you might be facing at the moment and we are ready to extend all possible help to solve them.
But such indiscipline in attendance cannot continue.
Sincerely,
Signature and name
TEMPLATE 3
To: [employee name] Date:
Subject: Warning letter for submitting below par project.
This letter is a warning to you for not meeting the objectives of the project as detailed in the directives given.
You were asked to cover all the aspects, including (give the list to be covered). But you submitted an incomplete project with none of the metrics taken into account as mentioned in the project proposal.
Your manager regularly checked with you on the progress of the proposal and you assured her that you were following up and would be able to submit it on time. However, we have received and incomplete project, which we were unable to forward to the clientele. We have missed our deadline and the client has awarded the project to another organization.
Such below-par performance is unacceptable. If you need any assistance or have queries, please feel free to reach out to me or your supervisors anytime.
If your work is found to be consistently below average, we will be forced to end your employment. So please take this warning letter seriously as your work performance is under scrutiny.
Sincerely,
HR Manager Signature