A written warning in the UK is issued after a formal disciplinary hearing where the employer has found misconduct or poor performance proven. It must state the specific misconduct, the improvement required, the timescale, the consequence of no improvement, the duration the warning stays on file, and the right of appeal. A written warning issued without a prior hearing is procedurally unfair and can be challenged at an employment tribunal.
What is a written warning?
A written warning is a formal document issued to an employee following a disciplinary hearing. It sits above a verbal warning in the disciplinary process and below a final written warning.
There are two types:
- First written warning: issued for a first instance of misconduct or poor performance that is serious enough to require formal action but not so serious as to justify dismissal
- Final written warning: issued when a first written warning has not resulted in improvement, or when the misconduct is serious enough to go straight to a final warning
Both types put the employee on notice that further misconduct or failure to improve may result in dismissal.
When should you issue a written warning?
A written warning is appropriate when:
- The employee has committed misconduct that is more than minor but does not constitute gross misconduct
- Performance is below the required standard after informal management and/or a verbal warning
- The employee has already received a verbal warning for similar conduct within the warning's active period
You should not go straight to a written warning without a formal hearing, even if the evidence seems clear.
What a written warning must include
| Element | What to write | |---|---| | Date of issue | The date the letter is sent | | The specific misconduct or performance issue | Precise description, not vague language | | The evidence relied on | Summarise the key evidence discussed at the hearing | | The required improvement | Specific, measurable behaviour or performance target | | The timescale for improvement | A clear review date (e.g. 3 months) | | The consequence of no improvement | State that failure to improve may result in a final warning or dismissal | | Duration of the warning | How long it remains active on the employee's file | | Right of appeal | To whom, within what timescale | | Signature and name | Issuing manager |
How long does a written warning stay on file?
There is no legal minimum or maximum, but ACAS guidance and common practice suggests:
- First written warning: 12 months
- Final written warning: 12 to 24 months
After the warning expires, it should not be used as the basis for further disciplinary action. However, you may keep an expired warning on file permanently for reference — you simply cannot rely on it to justify escalating a new disciplinary matter.
First written warning vs final written warning
| | First written warning | Final written warning | |---|---|---| | Triggered by | First misconduct or poor performance | Repeat misconduct, or serious first offence | | Next step if not improved | Final written warning | Dismissal | | Typical duration | 12 months | 12 to 24 months | | Can lead to dismissal directly? | No (unless conduct worsens significantly) | Yes |
Some employers issue a final written warning for conduct that is serious but just below the threshold for gross misconduct. This is legitimate — but document the reasoning clearly.
Issuing the warning after the hearing
Do not issue the written warning at the end of the disciplinary hearing. Adjourn the hearing, take time to consider the evidence, then send the letter within a reasonable time — typically 1 to 5 working days.
This gives the impression of genuine consideration rather than a pre-determined outcome, which is important if the decision is later scrutinised by a tribunal.
Storing written warnings
Written warnings should be stored securely and separately from general personnel files — accessible to the issuing manager and HR, but not visible to colleagues. KornerIQ keeps disciplinary records in the employee documents module with date-stamped entries, so expiry dates are tracked automatically and warnings are retrievable if a later claim is made.
Frequently asked questions
Can an employee refuse to sign a written warning? Yes — an employee can refuse to sign. Signature is acknowledgement of receipt, not agreement with the content. If they refuse, note on the file that the warning was issued and the employee declined to sign. Send it by email with read receipt or recorded post.
Does a written warning show up on a DBS check? No. Internal disciplinary records are held by employers and are not disclosed on DBS checks. DBS checks relate to criminal records, not employment history.
Can I issue a written warning for a first offence? Yes — if the misconduct is serious enough to warrant it. You do not have to start at a verbal warning. ACAS guidance says employers should use the level of warning appropriate to the seriousness of the conduct.
What if I issue a written warning and the employee resigns? If the employee resigns in response to the warning, consider whether it could be constructive dismissal. If the warning was issued fairly and was proportionate, a resignation is unlikely to succeed as constructive dismissal. Keep all records.
Can I issue a written warning by email? Yes — an email with a PDF attachment is acceptable. Ensure you have evidence of delivery. An email that bounces or goes to a junk folder is not adequate service.
