How long can you work on a stretch assignment without being paid the higher rate before it would be classed as your substantive role? The acting-up role I have been doing is at a higher grade to my substantive post and I have been doing this higher role without the extra pay for 21 months.
This would depend on what has been agreed between the employee and employer.
If the employee has agreed to “act up” on an open-ended basis, but there is no written agreement in place, there is a risk that the arrangement could become permanent through custom and practice.
Where an employee assumes the job title, duties, responsibility and salary of the new role and there is no review of the arrangement, it is possible that the role could become permanent as more time passes.
If there is a written agreement in place, specifying the time frame over which the employee will “act up”, and what the terms governing the arrangement are, there is little risk that the arrangement will become permanent.
Where a time frame has not been specified, but it is set out clearly in writing that it is a temporary arrangement and there are reviews with the employee, again it is unlikely that it will be deemed to be a permanent promotion.
I would contact HR and write out exactly what has happened, using a time line stating you feel you should be offered a permanent promotion due to the amount of time you have been doing the acting up, with evidence of doing the acting up role. If you do not agree with the outcome I would ask to request a copy of the grievance policy and pursue that route.