What Evidence Do You Need to Prove Unfair Dismissal?
What Evidence Do You Need to Prove Unfair Dismissal?
Important: This guide provides general information about UK employment law. It is not legal advice and cannot account for your specific circumstances. Time limits for employment tribunal claims are strict. If you're considering a claim, check deadlines carefully and consider seeking professional advice.
Jurisdiction
This guide applies to England, Wales and Scotland. Employment law in Northern Ireland operates under separate legislation and procedures.
In brief: To prove unfair dismissal, you need evidence that your employer either didn't have a fair reason for dismissing you or didn't follow a proper dismissal process. Employment tribunals focus on documents, decision-making, and how the dismissal was handled. Most claims must be submitted within strict time limits (currently 3 months minus 1 day from dismissal), but gathering evidence matters much earlier — often before you even decide whether to make a claim.
Last updated: 6 February 2026 By Yerty, using employment tribunal decisions and UK legislation.
Key Terms
| Legal Term | What It Means in Plain English | Why It Matters |
|---|---|---|
| Legally fair reason | A valid, lawful reason your employer must have for dismissing you, e.g., misconduct, redundancy, or capability issues | If the reason is unfair or made up, your claim is stronger |
| Reasonable dismissal process | Following proper steps when ending your employment, like giving warnings, consulting, or following company procedure | Skipping steps can make even a fair reason become unfair |
| Evidence | Documents, emails, messages, payslips, or notes that prove what happened | Tribunals base decisions on facts, not opinions |
| Employment tribunal | A legal body that decides if your dismissal was fair or unfair | Where you submit your claim and where disputes are resolved |
| Strict time limits | Deadlines for starting your claim (currently 3 months minus 1 day from dismissal) | Filing late can prevent you from getting compensation |
| Range of reasonable responses | Tribunals check whether your employer acted within a reasonable set of choices when dismissing someone | Shows why some dismissals are legally fair even if they feel unfair from your perspective |
This article helps you understand the types of evidence you need to consider for unfair dismissal.
Can You Prove Unfair Dismissal? A Quick Assessment
At its core, proving unfair dismissal usually involves showing one or both of the following:
- Your employer did not have a potentially fair reason for dismissing you, or
- The dismissal process was seriously flawed
Strong cases often include both.
Employment tribunals do not decide whether dismissal felt harsh, upsetting, or unjust. They assess whether the employer acted within what the law calls a "range of reasonable responses."
It's important to remember, as with all employment cases, that there are strict deadlines. The current time limit for unfair dismissal claims is 3 months minus 1 day from dismissal. From no earlier than October 2026, this is expected to increase to 6 months under the Employment Rights Act 2025. Before submitting a tribunal claim, you must notify ACAS for early conciliation — always start that process well before the deadline.
Evidence often becomes relevant before any claim: during grievances, internal discussions, or when deciding whether professional support may be useful.
You can learn about eligibility basics in this guide: Unfair Dismissal: Your Rights, Time Limits & What To Do
How Employment Tribunals Decide Unfair Dismissal Cases
Employment tribunals typically consider these questions:
- Was there a dismissal?
- What reason does the employer rely on?
- Is that reason potentially fair in law?
- Did the employer act reasonably in treating it as sufficient reason to dismiss?
When collecting evidence, it helps to consider and be able to demonstrate these core areas.
The responsibility for proving fairness is shared between employer and employee. First, the employer must show they had a potentially fair reason for dismissing you. Then, you can explain why the dismissal may still be unfair. Even if the employer's concerns were genuine, the dismissal can still be considered unfair if the process they followed was unreasonable.
The Five Potentially Fair Reasons for Dismissal
Defined by the Employment Rights Act 1996, employers usually rely on one of the following.
1. Conduct: Examples include misconduct or breaches of workplace rules.
Tribunals may examine: investigation records, disciplinary hearing notes, whether allegations were clearly explained, opportunity to respond, and consideration of alternatives. Some common issues include no investigation, decisions made in advance, or policies ignored.
2. Capability: Relates to performance or health.
Tribunals may examine: performance reviews, written warnings, support or training offered, time allowed to improve, and occupational health input (where relevant). A single poor review rarely justifies dismissal alone.
3. Redundancy
Tribunals may examine: whether redundancy was genuine, selection criteria, consultation records, and alternative roles considered. If the role continues under another name, unfairness may be inferred.
4. Statutory illegality: Where continued employment would break the law.
Tribunals may examine: whether illegality genuinely applied, steps taken to avoid dismissal, and alternatives explored.
5. Some other substantial reason (SOSR): A broad category covering restructuring or breakdown in trust.
Tribunals may examine: whether the reason was genuinely substantial, whether dismissal was proportionate, and whether alternatives were explored.
What Evidence Employment Tribunals Prioritise
Before you make a claim, it helps to understand what tribunals look for. When it comes to evidence, quality often matters more than quantity. Written records, clear timelines, and well-documented decision-making are usually more persuasive than large volumes of unorganised information.
Key Evidence Categories
| Type of Evidence | What It Includes | Why It Matters |
|---|---|---|
| Contracts | Employment contracts, terms of employment | Shows your legal rights and obligations, which can be compared to employer actions |
| Written evidence | Emails, messages, dismissal letters, meeting notes | Clear written records help tribunals understand what was communicated and when |
| Internal policies | Company handbooks, procedures, disciplinary rules | Demonstrates whether the employer followed their own processes |
| Witness statements | Notes or statements from colleagues | Provides corroboration and insight into events from a neutral perspective |
It's not always a bad thing if you don't have a particular document. In some circumstances, the absence of a document can matter as much as having one. For example, if you never received an employment contract, or the company lacks internal policies.
A Clear Timeline
When pulling together your evidence, building a timeline can strengthen your case and more clearly show the series of events. Timelines can reveal sudden escalation, predetermined decisions, or retaliatory patterns. For example: grievance raised → dismissal days later with no warnings.
Process Failures
Employers must follow fair procedures. If the employer did not follow a fair, reasonable process this can be grounds for unfair dismissal. Common indicators of an unfair process include: no investigation, no hearing, no warnings, no appeal, or the employer ignoring its own rules.
You can learn more about ACAS' expectations on fair procedures here: ACAS: Following a fair dismissal procedure
Witness Evidence
Witness statements can be a powerful form of evidence. Witnesses may confirm what was said, how long meetings lasted, or whether decisions felt pre-made. Perfect recall is not required.
Comparative Treatment
It's also worth considering whether you can demonstrate that others were treated more leniently in similar situations. This can strongly support unfairness.
Evidence by Type of Dismissal
Evidence in unfair dismissal claims varies depending on the stated reason for dismissal, as the tribunal must determine whether the employer acted reasonably. The main variations include misconduct or gross misconduct, capability or performance, redundancy, constructive dismissal, automatically unfair dismissal, and SOSR.
For constructive dismissal, the evidence focus shifts to employer conduct — see: Constructive Dismissal: When You Can Treat Yourself as Dismissed
Automatic unfair dismissal is explained fully here: 60 Grounds for Automatic Unfair Dismissal
What Missing Evidence Can Reveal
Sometimes it is revealing where evidence is absent. When there are no written warnings, no investigation notes, or no consultation records, that absence itself may support the argument of unfairness.
Common gaps that tribunals may note:
- No warnings before dismissal
- No investigation notes
- Vague or shifting dismissal reasons
- No consultation records
- No appeal offered
If something would normally be documented and isn't, that gap may work in your favour.
Interim Relief: The 7-Day Deadline You Cannot Miss
If you were dismissed for certain automatically unfair reasons — such as making a protected disclosure (whistleblowing), carrying out health and safety activities, trade union membership or activities, or acting as an employee representative — you may be able to apply for interim relief.
Interim relief is an emergency application asking the tribunal to order your employer to keep paying you (or re-engage you) until your full case is heard. If granted, it preserves your income while you wait for the tribunal hearing, which can take months.
The deadline is 7 days from the effective date of termination — this is one of the shortest deadlines in employment law. There is very limited scope for extension. If you miss it, interim relief is no longer available, even if the rest of your unfair dismissal claim is still in time.
What you need to do
- Act immediately. Seven days is calendar days, not working days. If you were dismissed on a Friday, the deadline is the following Friday.
- Submit your tribunal claim (ET1) within 7 days. The interim relief application is made alongside your tribunal claim — you cannot apply for interim relief without also filing the claim itself.
- ACAS early conciliation may not be required. If your claim is only for unfair dismissal with an interim relief application, you do not need to notify ACAS first. However, if you are also making other claims (for example, discrimination), you will need to notify ACAS for those. If in doubt, contact ACAS immediately — they can advise quickly.
- Gather key evidence fast. You won't need a full case at this stage, but the tribunal will want to see that your claim has a "pretty good chance" of succeeding. A dismissal letter, any whistleblowing disclosures, or evidence of protected activity can help.
What interim relief does not do
Interim relief does not decide your case. It is a holding order. If the tribunal grants it, your employer must continue paying you (or pay compensation in lieu) until the full hearing. If it is refused, your unfair dismissal claim continues as normal — you have not lost anything by applying.
Not all unfair dismissal claims qualify for interim relief. It is only available for specific automatically unfair reasons. If your dismissal was for ordinary unfair dismissal (for example, conduct or capability), interim relief does not apply.
For more detail: ACAS: Interim relief
Time Limits and Early Action
Time Limits
It's essential to know how long you have to bring a claim to an employment tribunal:
- Current limit: 3 months minus 1 day from the effective date of termination (when your employment ended). This is not always the same as the date on your dismissal letter.
- From no earlier than October 2026: this is expected to extend to 6 months under the Employment Rights Act 2025.
If interim relief applies to your situation, remember that the 7-day deadline comes first — see the section above.
Before submitting a tribunal claim, you must notify ACAS for early conciliation. The time spent in early conciliation may extend your deadline, but you should not rely on this — always start the process well before the 3-month deadline.
Missing these deadlines can prevent you from making a claim, regardless of how strong your evidence is.
For more detail on deadlines: Workplace Deadlines and Time Limits
Why Evidence Matters Early
Even though most claims never reach a tribunal, collecting evidence early can make a difference. Evidence helps you:
- Check whether something was legally wrong before deciding on next steps
- Support grievance feedback if you raise concerns internally
- Inform your options and plan next steps with clarity
- Encourage early resolution, avoiding the stress and cost of a tribunal
Start collecting evidence as soon as possible — during grievances, when assessing your options, or while understanding potential risks. Delays can weaken a case because documents can disappear and memories fade.
How the Employment Rights Act 2025 Affects Proving Unfair Dismissal
The Employment Rights Act 2025 received Royal Assent on 18 December 2025. It changes who can bring unfair dismissal claims and some of the protections available, but it does not change how proof works at tribunal.
Key Changes
Already in force (18 February 2026):
- Dismissal for taking part in industrial action is now automatically unfair at any point — the previous 12-week limit has been removed.
From no earlier than October 2026:
- Tribunal time limits are expected to extend from 3 months to 6 months.
- Employers will face a strengthened duty to take "all reasonable steps" to prevent sexual harassment, including from third parties.
From January 2027:
- The qualifying period for ordinary unfair dismissal reduces from 2 years to 6 months. This means more employees will be able to challenge unfair treatment.
- The compensation cap for unfair dismissal claims is being abolished. See: Compensatory Award for Unfair Dismissal
Dates may still change — check the latest position before relying on them. For the latest implementation dates: GOV.UK: Employment Rights Act implementation timeline
What Hasn't Changed
Tribunals still assess evidence the same way. Process failures remain central — employers must still follow fair procedures. While more people will be eligible to claim, the standards of evidence required remain the same.
What to Do Next
If you believe you've been unfairly dismissed, the first step is to understand your rights and whether you're eligible to make a claim. Knowing this early helps you make informed decisions and plan your next steps.
Yerty can guide you in understanding your rights, identifying what evidence is needed, and building your case and timeline. For many employees, combining Yerty's tools with legal advice from a solicitor works best: Yerty helps you organise and understand your situation, while solicitors advise on legal strategy and represent you if needed.
Even if you plan to use a solicitor, starting to gather evidence early — including documents and a clear timeline — can strengthen your case and save time.
When Legal Advice May Be Needed
You might consider seeking a solicitor if:
- Your claim overlaps with other issues, such as discrimination or harassment
- The potential compensation is high
- The facts of the case are heavily disputed
- Your employer has legal representation
For the full step-by-step overview: Unfair Dismissal: Your Rights, Time Limits & What To Do
For eligibility if you have less than 2 years' service: Unfair Dismissal Under 2 Years: Can You Still Claim?
Frequently Asked Questions
How hard is it to prove unfair dismissal?
It depends on eligibility, evidence quality, and process failures. Clear documentation and procedural issues often strengthen cases. Strong cases usually combine both a questionable reason and a flawed process.
Do I need written evidence?
Written evidence helps, but tribunals can also rely on witness testimony, especially where documents should exist but don't. The absence of documents that should have been created (like investigation notes) can itself support unfairness.
Can conduct be a fair reason for dismissal?
Yes, but only if the investigation and disciplinary process were reasonable. A genuine belief in misconduct must rest on a reasonable investigation that gave you a fair chance to respond.
Is evidence useful if I never make a claim?
Yes. Evidence strengthens grievances, clarifies your options, and preserves your choices. Many disputes are resolved through internal processes or early settlement without ever reaching a tribunal.
Do I need to contact ACAS before making a claim?
Yes. Before submitting a tribunal claim, you must notify ACAS for early conciliation. This is a mandatory step for most unfair dismissal claims. You should do this well before your 3-month deadline.
What is the time limit for an unfair dismissal claim?
Currently, the deadline is 3 months minus 1 day from the effective date of termination. From no earlier than October 2026, this is expected to extend to 6 months under the Employment Rights Act 2025. You must notify ACAS for early conciliation before submitting a claim.
What is interim relief and does it apply to me?
Interim relief is an emergency application to the tribunal asking your employer to keep paying you until your full case is heard. It is only available if you were dismissed for specific automatically unfair reasons — such as whistleblowing, health and safety activities, or trade union activities. The deadline is 7 days from the effective date of termination, making it one of the most urgent deadlines in employment law. If your claim is only for unfair dismissal with interim relief, you do not need to notify ACAS first — but you do if you are also making other claims alongside it.
Sources
- Employment Rights Act 1996
- Employment Rights Act 2025
- GOV.UK: Plan to Make Work Pay — Timeline Update (3 February 2026)
- ACAS: Dismissals — following a fair procedure
- ACAS: Making a claim to an employment tribunal
- Published employment tribunal decisions (England, Wales and Scotland)