Most employment tribunal claims must begin with Acas Early Conciliation before you submit an ET1 claim form, usually within three months less one day of the incident or dismissal. If conciliation does not resolve the dispute, you can apply online and your case may be listed at the Cardiff Employment Tribunal or another suitable venue. Keep contracts, payslips, correspondence and records showing what happened and when. Time limits are strict, so consider speaking promptly to a solicitor regulated by the SRA or checking the latest guidance on GOV.UK and Acas.