How to Write a Disciplinary Letter: A Plain English Guide for UK Employers

A disciplinary letter that is poorly written or legally incomplete can turn a straightforward conduct issue into an employment tribunal claim. This guide tells you exactly what to include in each type of letter - from the initial invitation to the outcome - and what wording to use.

What is a disciplinary letter?

A disciplinary letter is formal written communication from an employer to an employee about a conduct or performance concern. There are three main types you need to know: the invitation letter (calling the employee to a disciplinary meeting), the outcome letter (confirming the result of the meeting) and the appeal outcome letter (responding if the employee appeals).

Each type has specific legal requirements. Missing any of them creates tribunal risk.

Before you write anything: follow the ACAS Code

The ACAS Code of Practice on Disciplinary and Grievance Procedures is not optional. Employment tribunals are required by law to consider it when assessing whether a dismissal was fair. If you deviate from it without good reason, any compensation awarded against you can be increased by up to 25 percent.

The Code requires you to investigate before acting, invite the employee in writing, hold a meeting before imposing any sanction, allow them to be accompanied and offer the right of appeal. Every disciplinary letter you write sits within that framework.

The invitation letter

This is the letter you send before the disciplinary meeting. It must include:

The nature of the alleged misconduct or performance concern, stated clearly and specifically. Vague allegations - "your attitude has been unacceptable" - are not sufficient. Specific allegations - "on three occasions between 12 April and 29 April 2026 you spoke to customers in a manner that generated written complaints" - are sufficient.

The date, time and location of the disciplinary meeting. Give at least 48 hours notice and ideally five working days.

The right to be accompanied. State this explicitly. The employee may bring a trade union representative or a work colleague. Do not omit this line.

The potential outcome. If dismissal is possible, say so. The employee has the right to know the severity of what they face so they can prepare properly.

Any evidence you intend to use. Attach copies or tell them where to access them. Presenting new evidence at the meeting without prior notice is procedurally unfair.

Example invitation letter wording:

Dear [Name],

I am writing to invite you to a disciplinary hearing to discuss a concern about your conduct.

The concern is as follows: [state the specific allegation].

The meeting will take place on [date] at [time] at [location]. You have the right to be accompanied by a trade union representative or a work colleague of your choice. Please let me know if you intend to bring someone.

I enclose [list evidence]. Please review this before the meeting.

The outcome of this meeting could result in [a first written warning / a final written warning / dismissal]. You will have the opportunity to respond fully to the concerns raised.

Yours sincerely, [Your name]

The outcome letter

This confirms the decision reached after the meeting. Send it within a few days of the meeting at the latest. It must include:

• →The finding - what was concluded about the allegation
• →The sanction imposed and the reason for it
• →The duration of any warning - state the exact end date or period
• →What improvement is expected and by when, if relevant
• →The right of appeal, who to appeal to and the deadline
• →The date of the letter

First written warning - example wording:

Dear [Name],

Further to the disciplinary hearing held on [date], I am writing to confirm the outcome.

Having considered the evidence and your response, I have concluded that [state finding]. As a result, I am issuing you with a first written warning.

This warning will remain on your record for [6 / 12] months from the date of this letter. If there is no recurrence during this period, it will be disregarded for disciplinary purposes.

If a further conduct issue arises during this period, this may result in a final written warning or dismissal.

You have the right to appeal this decision. Appeals must be made in writing to [name] within five working days of receiving this letter.

Yours sincerely, [Your name]

If the outcome is dismissal, the letter must also confirm the notice period or payment in lieu of notice, outstanding holiday pay and the date employment ends. Keep the tone factual. This letter may be read in an employment tribunal.

Common mistakes that create tribunal risk

Not investigating before issuing the invitation. You must gather basic facts first. Even a short investigation - speaking to witnesses, reviewing records - is required before you call a meeting.

Being vague about the allegation. The employee must know specifically what they are accused of so they can respond. Vague allegations deny them a fair hearing.

Not offering the right to be accompanied. This is a statutory right. Breach it and any subsequent action is automatically unfair.

Issuing the outcome verbally without following up in writing. The written letter is the legal record.

Setting no duration on the warning. If you do not state how long a warning lasts, it can theoretically last indefinitely, which causes problems later.

What changes from January 2027

How Birchlow helps

Birchlow generates legally compliant disciplinary letters automatically. When you log a disciplinary case on the platform, it produces the invitation letter, the outcome letter and the appeal outcome letter - all pre-populated with the correct statutory language, updated to reflect current employment law. You review, personalise and send.