What Counts as Gross Misconduct? A Plain English Guide for UK Employers

Gross misconduct is the most serious category of employee behaviour - and one of the few grounds on which you can dismiss someone without notice. But the term is widely misunderstood and many employers either use it too readily or fail to act on genuine cases because they are unsure of the process. This guide tells you what counts as gross misconduct, how to handle it and where employers go wrong.

What gross misconduct actually means

Gross misconduct is conduct so serious that it fundamentally destroys the trust and confidence between employer and employee, making the continuation of the employment relationship impossible. It is not simply bad behaviour. It is behaviour that crosses a line - a line serious enough to justify ending the employment relationship immediately and without notice.

The legal test is not whether the behaviour was wrong. It is whether a reasonable employer, having carried out a reasonable investigation, could conclude that the conduct was so serious as to justify dismissal.

Common examples of gross misconduct

Employment law does not publish a definitive list. What counts as gross misconduct depends partly on your sector and your written policies. That said, the following categories are widely accepted by employment tribunals as capable of amounting to gross misconduct:

Theft or fraud. Stealing from the business, customers or colleagues. Falsifying timesheets, expenses or records. This is the most common category and one of the clearest.

Violence or threatening behaviour. Physical assault of a colleague, customer or member of the public. Serious threats of violence. Behaviour that makes others feel unsafe.

Serious health and safety violations. Deliberately disabling safety equipment, working under the influence of alcohol or drugs in a safety-critical role, ignoring mandatory safety procedures in a way that could cause injury or death.

Gross insubordination. Refusing a reasonable management instruction in a way that is wilful and deliberate - not simply disagreeing, but refusing to comply in a way that undermines authority.

Serious breach of confidentiality. Sharing commercially sensitive information with a competitor. Leaking customer data. This is particularly relevant for trades businesses with client lists and pricing information.

Sexual harassment or serious discrimination. Any conduct of a sexual nature directed at a colleague or customer or behaviour that constitutes unlawful discrimination on a protected characteristic.

Serious misuse of company property or systems. Using company vehicles, equipment or IT systems for illegal activity or in serious breach of your policies.

What does not count as gross misconduct

This matters as much as the list above. The following are often treated as gross misconduct by employers when they should not be:

A single episode of lateness, even a serious one. Poor performance over time. A heated argument that did not involve threats or physical contact. Making a genuine mistake, even a costly one. Taking a sick day the employer believes is not genuine - unless you have clear evidence of dishonesty.

Using the gross misconduct label incorrectly - dismissing without notice for something that does not meet the threshold - is one of the most common causes of successful unfair dismissal claims against small employers.

The process you must follow

Even for the most obvious cases of gross misconduct, you must follow a fair process. Skipping the process because you are certain of what happened is the single most common mistake employers make.

Step one: Investigate. Gather the facts. Speak to witnesses. Review any physical or documentary evidence. If necessary, suspend the employee on full pay while you do this.

Step two: Invite to a disciplinary meeting in writing. The invitation letter must state the allegation, the date and time of the meeting, the right to be accompanied and that dismissal is a possible outcome.

Step three: Hold the meeting. Give the employee the chance to respond to the allegation. Listen. Consider any explanation they offer, even if you are sceptical.

Step four: Decide and confirm in writing. If you conclude the misconduct occurred and dismissal is the right outcome, confirm this in a dismissal letter that includes the right of appeal.

Step five: Handle the appeal. If the employee appeals, a different manager should hear it if possible.

The entire process from suspension to outcome can be completed in a week for straightforward cases. It does not need to be slow to be fair.

Summary dismissal: dismissal without notice

If you conclude that genuine gross misconduct has occurred and you follow a fair process, you can dismiss the employee without notice - or without paying them in lieu of notice. This is called summary dismissal.

You must still pay any outstanding holiday pay. You must still confirm the dismissal in writing. You must still offer the right of appeal.

What you do not have to pay is the notice period - the weeks or months of contractual notice that would normally apply.

What changes from January 2027

How Birchlow helps

Birchlow generates the disciplinary letters you need for a gross misconduct case automatically - the suspension letter, the invitation to a disciplinary hearing and the dismissal outcome letter - all updated to reflect current employment law. The platform also logs each stage of the process, so if a claim is made, you have a complete timestamped record of how you handled it.