A formal workplace grievance is a written complaint made to your employer about a work-related matter that you have not been able to resolve informally. It triggers your employer's formal grievance procedure, which must comply with the ACAS Code of Practice on Disciplinary and Grievance Procedures. Your employer must invite you to a grievance meeting, allow you to be accompanied by a colleague or trade union representative, and give you the right to appeal their decision.

Common grounds include bullying or harassment (by a manager or colleague), discrimination on grounds of age, sex, race, disability, religion, or sexual orientation (Equality Act 2010), unfair treatment in pay, promotion, or working conditions, breach of your employment contract, health and safety failures, and whistleblowing concerns (protected disclosures under the Public Interest Disclosure Act 1998).

Raising a grievance does not make you immune from dismissal, but dismissing an employee in retaliation for raising a legitimate grievance is automatically unfair dismissal under the Employment Rights Act 1996 and, where discrimination is involved, unlawful under the Equality Act 2010. Keep records of all communications around your grievance in case you need to demonstrate a causal link.

If you are considering resigning due to your employer's conduct, you should raise a grievance first. Resigning without raising a grievance can weaken a constructive dismissal claim, as tribunals expect employees to have given their employer an opportunity to address the issue. If the employer's response to your grievance is inadequate, that strengthens your case that you had no option but to resign.