The ACAS Code is not legally binding, but employment tribunals take it very seriously. It sets the standard your disciplinary and grievance processes are judged against, and an unreasonable failure to follow it can increase a tribunal award by up to 25%.
In practice, treat it as the minimum. Following it makes your process defensible. Ignoring it hands the other side an easy point.
Important
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.
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.