The safest path is relying on an express term in the employee’s contract enabling you to modify the position from FT to PT, or vice versa. If there is no such provision, you have two basic choices:
Option 1: Impose the change unilaterally. This is risky. The employee’s perception that this is a fundamental change to his/her employment would be on target, which means that you’d be at risk of a constructive dismissal claim. You MIGHT be able to avoid this if one or more of the following things are true (the more, the better):
- There was an implied agreement or understanding between you that such a change was likely or at least possible
- You’ve unilaterally made similar changes to his/her employment in the past with no objection
- The change is essential to a legitimate business purpose
- Such changes are common in your industry
Option 2: Negotiate a new position with the employee. Either modify or replace the current contract. If the employee objects, you may want to advise her/him that the alternative is termination. Of course, termination would be without cause and termination notice would be due. But the employee may still prefer a shift to FT to totally forfeiting the job.
Good luck and hope this helps. Glenn