If you have a problem or a complaint at work then you need to think about whether you should raise a grievance.
A grievance can be made at any time - even in response to a disciplinary or redundancy process against you if you consider such a process unfair.
A grievance puts down a marker that you are unhappy about something and can sometimes stop action taken by your employer against you whilst your grievance is being investigated. It can also frustrate your employer’s ability to proceed in the way they had originally intended.
A failure to raise a grievance in writing does not prevent you from bringing a tribunal claim, but it does mean any damages you are awarded at tribunal can be reduced by up to 25%.