A plain-English guide for both employers and employees on constructive dismissal resignation letters. It outlines key rules, common risks and typical steps so you can understand the issues before deciding what to do next.

Constructive dismissal resignation letter: practical UK guide

A constructive dismissal resignation letter explains, in plain terms, that you’re resigning in response to your employer’s serious breach of contract and states the key incidents and dates. Seek legal advice before resigning, keep it factual, resign promptly, and start ACAS early conciliation if you intend to claim in the employment tribunal.

Key takeaways

• Constructive dismissal is a type of unfair dismissal. You must usually have 2 years’ service to claim, unless an automatic unfair reason or discrimination applies.

• Three core tests: a fundamental breach by the employer, resignation in response to that breach, and acting without undue delay (to avoid ‘affirmation’).

• Your letter should be factual, clear on reasons and dates, and avoid emotive language. Do not use ‘without prejudice’ unless discussing settlement.

• Consider alternatives first, if time allows: grievance, adjustments, mediation or a protected conversation (pre‑termination negotiations).

• If you pursue a claim, notify ACAS for early conciliation and watch the three months minus one day time limit from the effective date of termination.

Overview

‘Constructive dismissal’ arises when an employee resigns because s/he believes the employer has fundamentally breached the employment contract, for example by seriously undermining trust and confidence. The statutory definition appears in section 95(1)(c) of the Employment Rights Act 1996. Case law confirms the contract‑law test applies.

For employers: duties and risks

Legal duties and risks

Treat concerns promptly and fairly. Follow the ACAS Code for grievances. Avoid behaviour that could amount to a repudiatory breach, such as unilateral pay cuts, unsafe work, or ignoring complaints. Document decisions, keep minutes, and provide timely responses. Settlement discussions should be separate and clearly labelled as such when appropriate.

Process you must follow

• Acknowledge any resignation letter the same day, confirm last day (effective date of termination) and next steps for handover/pay.

• Invite the employee to a grievance meeting where appropriate.

• Preserve all documents and messages. Avoid retaliatory comments or references.

• Consider without prejudice settlement only when negotiating terms, not in general correspondence.

Common pitfalls for employers

• Delays or cursory responses to grievances.

• Inconsistent treatment and poor record‑keeping.

• Breaching confidentiality.

• Overlooking ACAS Code duties, risking up to a 25% uplift on awards.

For employees: rights and typical steps

Do I qualify?

Most claims need two years’ service, unless the reason is automatically unfair (for example discrimination, health and safety, whistleblowing). Keep evidence of the breach and your timeline.

What to do next

• Write down what happened, with dates, witnesses and documents.

• If there is time, raise a formal grievance and say if you’re working ‘under protest’.

• Get legal advice before resigning or sending any letter.

• Decide whether to resign immediately or on short notice; act promptly to avoid affirming the breach.

• Send a factual resignation letter explaining you are resigning in response to the breach, and keep copies.

• If you intend to claim, start ACAS early conciliation and monitor the tribunal deadline.

How long it takes

Early conciliation typically lasts for 6 weeks. Employment tribunal claims have strict time limits. Settlements may resolve matters more quickly.

Typical outcomes

• Internal resolution or adjustments following a grievance.

• Settlement agreement with agreed terms (you cannot then bring a tribunal claim about the same issue).

• Tribunal claim for constructive unfair dismissal (and possibly discrimination).

Examples

Example 1 (employee): After reporting ongoing bullying, no action was taken and the employee’s hours were cut without consent. The employee raised a grievance and stated they were working under protest. Following no meaningful response, they resigned promptly citing a fundamental breach and started ACAS early conciliation.

Example 2 (employer): An employee alleged unpaid overtime and harassment. HR acknowledged the grievance within 24 hours, paused any changes, investigated, and offered explanations and solutions. Clear records and timely steps avoided escalation and reduced legal risk.

FAQs

Do I have to resign immediately?

Not always, but delay can suggest you accepted the situation (‘affirmation’). If you delay, explain why (for example awaiting a grievance outcome) and make it clear you are reserving your rights.

Should I work my notice?

You can resign with or without notice depending on the breach. Working a short notice period is not fatal, but a long delay can undermine your case. Check your contract and take advice, as by not giving notice you may be found in breach of contract should your claim fail

What should my resignation letter include?

We strongly recommend you take legal advice on this as a poorly drafted letter can be fatal to a claim.  It needs to provide a concise explanation of the breaches and that you are resigning in response to your employer’s fundamental breach (constructive dismissal).

Should I mark the letter ‘without prejudice’?

No, not for a resignation itself. Use ‘without prejudice’ only for genuine settlement negotiations, and ‘protected conversation’ for pre‑termination negotiations under section 111A ERA.

Do I need two years’ service?

Usually yes for ordinary unfair dismissal claims, including constructive dismissal, but not for discrimination or certain automatic unfair reasons. Get advice on your specific facts.

What are the time limits?

In most cases, you must start ACAS early conciliation within three months minus one day of the effective date of termination. The ACAS early conciliation process affects the time limit—check the rules carefully.

When to get advice and next steps

Before resigning. The wording, timing and evidence make a huge difference. A short call now can avoid expensive mistakes later.

Speak to our team about constructive dismissal and resignation letters. 0800 915 7777 or hello@kilgannonlaw.co.uk

This page provides general information only, based on UK employment law as at the date of publication. It is not legal advice and must not be relied on as such. Outcomes depend on your circumstances. Reading this page or contacting us does not create a solicitor‑client relationship. Please do not include confidential information in your first message.