• subject always to the discretion of the employment tribunal, it is generally possible to amend an ET1 Claim Form to introduce a new cause of action provided it relies on facts already pleaded. This is so even if it would be out of time to seek to introduce the new cause of action as a separate claim.
  
• a tribunal in considering whether to allow an amendment to a Claim Form should have regard to all the circumstances of the case and consider any injustice, prejudice or hardship which may be caused to any of the parties if the proposed amendment were allowed or refused.

For relevant general notes see Time-limits/extension of time-limits and/or Procedure of Employment Tribunals/amending claims .