This article applies to England, Wales and Scotland. Northern Ireland has a separate tribunal system.
In brief: Vexatious means a complaint or claim with no real basis that puts the other side to trouble out of proportion to anything it could achieve. An employer using the word about your grievance changes nothing in law. At tribunal it can lead to strike-out or a costs order, but in published decisions from 2017 to 2025 a costs order against the claimant appears in 1.2% of cases.
Last updated: 2 September 2026
By Yerty | Checked against the Employment Tribunal Procedure Rules 2024, Attorney General v Messi [2026] EAT 34, the Equality Act 2010 and current Acas guidance. Figures from Yerty's analysis of published tribunal decisions; method stated below.
Your employer, or their solicitor, has described your grievance or your tribunal claim as vexatious. It is a word chosen to make you stop. Before you decide anything, it is worth knowing what it actually means, what it can and cannot lead to, and how often it leads to anything at all.
Important: This guide provides general information about employment law in England, Wales and Scotland. Yerty is not a law firm and does not provide legal advice. If you have received a costs warning, a deposit order or a strike-out application, consider speaking to a solicitor or an advice service before you respond.
What Does Vexatious Actually Mean?
In everyday use, vexatious means done to annoy or harass. In tribunal law it is wider than that. The test the Employment Appeal Tribunal applied in Attorney General v Messi [2026] EAT 34 is that proceedings are vexatious where they have little or no basis in law and their effect, whatever you intended, is to put the other side to inconvenience and expense out of all proportion to anything the claim could achieve. So it is not an accusation about your motives. It is a claim that your case has no real foundation. That is the thing to test the word against: not "am I being spiteful?" but "is there a genuine dispute here with a legal basis?"
If there is, the word does not apply, however often it is repeated.
Can My Employer Ignore My Grievance Because They Say It Is Vexatious?
No. There is no legal definition of a vexatious grievance, so the label is an opinion. The Acas Code of Practice on Disciplinary and Grievance Procedures (the 2015 Code, still in force) expects an employer that receives a formal grievance to hold a meeting without unreasonable delay, investigate where necessary, give a decision and allow an appeal. In qualifying tribunal proceedings, an unreasonable failure to follow the Code can lead to compensation being adjusted by up to 25%.
The one situation where the word has some substance is repetition. If you have already raised the same complaint, had it investigated, decided and appealed, and you raise it again with nothing new, an employer may reasonably decline to run the whole process a second time. Whether that is reasonable depends on the circumstances. A grievance that raises a new matter, or new evidence on an old one, is a different grievance and the Code applies to it.
If you want the grievance to be hard to dismiss, keep it short, set out what happened with dates, say what you tried informally or why you did not, and say what outcome you want. Acas's draft 2026 Code (published 30 July 2026, under consultation until 23 September, not yet in force) says exactly that: a short, clear written grievance will often be enough, and it should state the desired outcome where possible. It also says a formal grievance can properly be raised straight away where informal resolution is not appropriate, such as serious misconduct.
Can They Punish Me for Raising It?
If your grievance alleged discrimination, harassment or victimisation, raising it is a "protected act" under section 27 of the Equality Act 2010. Treating you worse because you raised it is victimisation, which is unlawful in itself and can be claimed at tribunal separately from the original complaint. The only way that protection is lost is where a false allegation was made in bad faith. Calling the grievance vexatious does not remove the protection; a tribunal would have to find that you made a false allegation dishonestly, and an allegation that turns out to be wrong but was genuinely believed keeps the protection.
If your grievance was about something other than discrimination, such as pay, hours or a contractual term, dismissing you for asserting a statutory right can be automatically unfair under section 104 of the Employment Rights Act 1996, and any disadvantage short of dismissal is evidence in a later claim.
Could My Tribunal Claim Be Thrown Out?
It can, but the bar is high and the word "vexatious" is rarely the reason.
Under rule 38 of the Employment Tribunal Procedure Rules 2024, a tribunal may strike out all or part of a claim that is scandalous or vexatious or has no reasonable prospect of success, or where the way it has been conducted has been scandalous, unreasonable or vexatious. It can also strike out for non-compliance with orders, for not pursuing the claim, or where a fair hearing is no longer possible. You have to be given a reasonable opportunity to respond first, in writing or at a hearing.
For the "no reasonable prospect" ground, the appeal courts describe strike-out as a draconian step for clear-cut cases. Tribunals are particularly cautious where deciding the claim means resolving a dispute about what happened or why, which is most discrimination claims. A claim with a real factual dispute at its centre is not struck out because the employer disagrees with your account.
How often does it happen? In Yerty's analysis of published decisions from 2017 to 2025, 7,968 cases contain a strike-out. Scandalous or vexatious conduct was the ground in 260 of them. The common grounds are no reasonable prospect of success (2,627), the claim not being actively pursued (2,319) and non-compliance with orders (1,418). The practical lesson is that claims are far more often lost by not turning up, not replying and missing deadlines than by being called vexatious.
There is a middle step. Under rule 40, where a specific allegation has little reasonable prospect of success, the tribunal can require a deposit of up to £1,000 as a condition of continuing with it, taking your means into account. If you pay it and later lose that allegation for substantially the reasons the tribunal gave, you are treated as having acted unreasonably for costs purposes unless you show otherwise, and the deposit can go to the other side. If you win, it comes back. A deposit order is the tribunal telling you which part of your case it doubts; it is worth reading as advice.
Will I Have to Pay Their Legal Costs?
This is usually the real fear behind the word, and the answer is: probably not, and never simply for losing.
Unlike the civil courts, costs in the employment tribunal do not normally follow the event. Under rule 74 onwards, the tribunal must consider a costs order where a party has acted vexatiously, abusively, disruptively or otherwise unreasonably in bringing or conducting the claim, where the claim had no reasonable prospect of success, or where a hearing was postponed on an application made less than seven days before it. Other breaches of orders can also found an application. Even when one of those thresholds is met, ordering costs remains a discretion, and the tribunal may take your ability to pay into account.
How common is it? Across 125,778 published cases decided between 2017 and 2025, a costs order against the claimant appears in 1,537, which is 1.2%. Where the tribunal gave its reason, it cited unreasonable or vexatious conduct of the proceedings in 834 cases and no reasonable prospect of success in 370. Where an employer applied for costs, the tribunal granted the application in 1,326 cases and refused it in 1,060.
How much? Where an amount was stated, the median order was £2,809. A quarter were £1,000 or less, three quarters were under £8,000, and 103 sat at exactly £20,000, the ceiling for an order without a detailed assessment. Only 31 exceeded it.
Read together: the gateway that bites is conduct during the proceedings, more than twice as often as a claim being hopeless from the start. Costs risk is something you can largely control by complying with orders, attending hearings, and not continuing with a point once you have been shown clearly that it cannot succeed.
Method: cases with a final outcome in Yerty's published-decision set, disposed 2017 to 2025, deduplicated to case so a separate costs judgment is not counted twice. Settled, conciliated and withdrawn claims do not appear in published decisions, so these are shares of published decided cases, not of all claims brought. Rates are provisional until outcome extraction is complete; strike-out figures cover reasoned decisions only.
They Have Written to Say They Will Apply for Costs. What Now?
A costs warning letter usually arrives with the ET3 response to your ET1 claim, or before a hearing. It says the claim is vexatious or misconceived and that costs will be sought if you continue.
The letter is correspondence from the other side, not a decision. The tribunal has not seen it and has decided nothing. It has two purposes: to make you reconsider, and to show a tribunal later that you were warned and carried on. The second purpose is why its contents matter more than its tone.
Read the reasons. A letter that identifies a specific problem, such as the claim being out of time or your own account not amounting to the claim you have ticked, needs a real answer, and you may want advice on whether it is right. A letter that says "vexatious" and "misconceived" with no specific reason is asserting, not demonstrating. Decide whether to reply at all; in a significant case, get advice before sending anything substantive, because a long or angry reply becomes part of the conduct a tribunal later assesses. Keep the letter and anything you send back. Our guide to employment tribunal claims and what to expect covers the stages after the ET3, and our tribunal outcomes and success rates guide shows how claims that reach a hearing are decided.
What to Do Next
If it is your grievance: check it raises something new or something not yet decided, keep it short, say what you want, and note the date you raised it and anything that changes afterwards.
If it is your claim: identify the specific reason the other side says it cannot succeed, and work out whether you can answer it. Comply with every tribunal order on time. If a deposit order is made, treat the tribunal's reasons as the part of your case to strengthen or drop. For complex or high-value cases, or where a costs application has actually been made, you may want to speak with a solicitor.
Frequently Asked Questions
What does vexatious mean in employment law?
Proceedings with little or no legal basis whose effect is to put the other side to inconvenience and expense out of proportion to anything they could achieve. That is the test the EAT applied in Attorney General v Messi [2026] EAT 34. Intention to annoy is not required. Outside the tribunal, "vexatious grievance" has no legal definition.
Can my employer refuse to hear a grievance because it is vexatious?
Not on that basis alone. The Acas Code expects employers to hold a meeting, investigate and decide a formal grievance. Where the same complaint has already been decided and nothing new is raised, an employer may reasonably decline to repeat the process. Refusing a genuinely new grievance risks a 25% adjustment in qualifying tribunal proceedings.
How often do employment tribunals award costs against claimants?
In Yerty's analysis of 125,778 published cases decided between 2017 and 2025, a costs order against the claimant appears in 1,537, or 1.2%. The most common ground was unreasonable conduct of the proceedings. Losing a claim does not, by itself, lead to a costs order.
How much are costs orders in the employment tribunal?
In published decisions from 2017 to 2025 where an amount was stated, the median costs order against a claimant was £2,809. A quarter were £1,000 or less and three quarters were under £8,000. Orders above £20,000 require a detailed assessment and are rare: 31 in nine years.
What happens after a deposit order?
You pay up to £1,000 to continue with that allegation. If the tribunal later decides the allegation against you for substantially the reasons in the deposit order, you are treated as having acted unreasonably for costs purposes unless you show otherwise, and the deposit can go to the other side. If you succeed, the deposit is returned.
Is a costs warning letter a costs order?
No. It is correspondence from the respondent's representative. Only a tribunal can make a costs order, after an application and after you have had the chance to respond. The letter can be relevant to a later application, which is why its specific reasons deserve a careful read.
What is a vexatious litigant?
Someone the Employment Appeal Tribunal has made subject to a restriction of proceedings order under section 33 of the Employment Tribunals Act 1996, on the Attorney General's application, for habitually and persistently bringing vexatious proceedings without reasonable ground. Attorney General v Messi [2026] EAT 34 involved more than 50 claims. It is not a label an employer can apply to you, and an ordinary contested claim comes nowhere near it.
Sources
- Attorney General v Messi [2026] EAT 34, 3 March 2026 — https://assets.publishing.service.gov.uk/media/69a5bb73b346998e6646b5c6/The_Attorney_General_v_Ms_Sandra_Messi__2026__EAT_34.pdf
- The Employment Tribunal Procedure Rules 2024 (SI 2024/1155), rules 38, 40 and 74 onwards — https://www.legislation.gov.uk/uksi/2024/1155
- Equality Act 2010, section 27 (victimisation) — https://www.legislation.gov.uk/ukpga/2010/15/section/27
- Employment Rights Act 1996, section 104 (assertion of a statutory right) — https://www.legislation.gov.uk/ukpga/1996/18/section/104
- "Code of Practice on disciplinary and grievance procedures", Acas, 2015 — https://www.acas.org.uk/acas-code-of-practice-on-disciplinary-and-grievance-procedures
- "Code of Practice on disciplinary and grievance procedures (draft for consultation)", Acas, 30 July 2026 — https://www.acas.org.uk/about-us/acas-consultations/code-of-practice-disciplinary-grievance-2026/draft-code
- Yerty analysis of published Employment Tribunal decisions, 2017 to 2025 (method above)