Happens all the time, and it's often a real concern and a tactic at once. You've got a choice. Pause the disciplinary and deal with the grievance first, or run them together if they're closely linked. Either can be fair. What isn't fair is ignoring the grievance and ploughing on, because that's exactly what a tribunal will home in on later.
Base it on one thing: does the grievance affect whether the disciplinary is fair? If it's about the process, the investigator or the evidence, sort it before you go further. If it's unrelated, you can usually carry on and handle the grievance alongside. Either way, write down why you decided what you did, so it reads as considered rather than convenient.
Every situation has its own details, and those details change the right answer. For a read on yours, take the free Employee Situation Check or book a call.
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How to handle this, in a couple of minutes
Samantha talks through the practical steps.
General guidance to help you decide your next step, not legal advice. Employment law changes, so always check the current position for your own situation.