How to challenge unfair dismissal in the UK

You gave them six years. They gave you a week's notice and a letter with three sentences. No meeting. No warning. No process.

Being dismissed without proper procedure is one of the most disorienting things that can happen to you at work. One day you're employed. The next, you're not — and the reasons given either don't add up or aren't given at all. You're angry, you're anxious, and you don't know where to start.

Here is where to start. This guide covers your rights under UK law, what counts as unfair dismissal, the deadline that could end your case if you miss it, and the letter that puts your employer back on the defensive.

What counts as unfair dismissal under UK law

Under the Employment Rights Act 1996 (ERA 1996), sections 94–134A, employees with 2 or more years of continuous service have the right not to be unfairly dismissed. That means your employer needs a fair reason to dismiss you — and they need to follow a fair procedure in doing so. If either element is missing, the dismissal may be unlawful.

Fair reasons for dismissal

The law recognises five potentially fair reasons for dismissal. An employer who relies on any of these still has to show both that the reason is genuine and that dismissal was a reasonable response:

• Conduct — misconduct at work, including gross misconduct
• Capability — poor performance or ill-health affecting the ability to do the job
• Redundancy — the role no longer exists or the need for employees to do the work has diminished
• Statutory bar — continuing employment would break the law (e.g. a driver who loses their licence)
• Some Other Substantial Reason (SOSR) — a catch-all for legitimate business reasons that don't fit the other categories

Even where a fair reason exists, an employer who fails to follow a fair procedure — proper investigation, written notice, a hearing, the right to be accompanied, the right to appeal — can still lose at tribunal.

Automatically unfair dismissal — no 2-year service requirement

Some dismissals are automatically unfair from day one of employment — no 2-year qualifying period applies. These include dismissal for:

• Whistleblowing — making a protected disclosure under the Public Interest Disclosure Act 1998
• Pregnancy or maternity — any reason connected to pregnancy, maternity leave, or maternity rights
• Asserting a statutory right — e.g. demanding the national minimum wage, written terms, or paid annual leave
• Trade union activity — membership, participation in union activities, or collective bargaining
• Health and safety activities — raising health and safety concerns in good faith

If any of these apply to you, the 2-year rule does not block your claim.

The ACAS Code of Practice — and the 25% uplift

The ACAS Code of Practice on Disciplinary and Grievance Procedures sets the minimum standard for how employers must handle disciplinary matters. Employers are required to:

• Investigate the matter before taking action
• Notify the employee in writing of the allegation
• Hold a disciplinary hearing with the employee
• Allow the employee to be accompanied
• Offer a right of appeal against any sanction

Failure to follow the ACAS Code is not automatically fatal to the employer's case — but a tribunal can increase any compensation awarded to you by up to 25% if your employer unreasonably failed to comply. If your employer followed none of these steps, that 25% uplift applies.

How to challenge unfair dismissal: step by step

Do these in order. Every step matters.

What an unfair dismissal letter from Fight My Corner does

A formal letter is not a complaint. It is a legal document. Employers — especially smaller businesses — take a formal, legislation-citing letter very seriously because they know what it signals: you are informed, you are on the record, and you know the ET1 route.

A Fight My Corner unfair dismissal letter:

Smaller employers — without an in-house HR team or employment solicitor on retainer — often have no idea how exposed they are. A formal letter citing the legislation, the ACAS failures, and the tribunal route makes that exposure visible. Many employers choose to negotiate a settlement rather than face an Employment Tribunal, where even a successful defence costs time, legal fees, and management distraction.

Unfair dismissal compensation: what you could be awarded

If you win at an Employment Tribunal, compensation is made up of two parts:

The tribunal can also order reinstatement (getting your old job back on the same terms) or re-engagement (a comparable role with the same employer). In practice, most claims settle on compensation — but both remedies exist.

Remember: if your employer unreasonably failed to follow the ACAS Code, the compensatory award can be increased by up to 25%. If you yourself failed to follow an internal procedure without good reason, it can be reduced.

What Fight My Corner can't help with — and what to do instead

There are situations where the unfair dismissal route doesn't apply directly:

• Under 2 years' service — the standard qualifying period for unfair dismissal claims. Unless your dismissal falls into one of the automatically unfair categories above, you cannot bring an unfair dismissal claim.
• Zero-hours or self-employed — unfair dismissal rights belong to employees, not workers or the self-employed. If your employment status is unclear, that's worth exploring — but it's a distinct legal question.
• Redundancy disputes — if your employer is claiming redundancy but you believe it is a sham, or that you were selected unfairly, that is a different claim pathway with its own rules.

For complex cases — especially where automatic unfair dismissal, discrimination, or whistleblowing is involved — the stakes and the legal complexity rise significantly. We always recommend speaking to an employment solicitor or your trade union representative for cases of that nature. Many employment solicitors offer a free initial consultation, and Citizens Advice can help identify your options.