This is a common question in unionized workplace and the answer will depend, of course, not only on the particular wording of the collective agreement but on the underlying facts.
The recent case Nova Scotia arbitration award in Canadian Union of Public Employers, Local 3698 v Colonial Community Services, (2013) CanLII 10166 (NS LA) considered a grievance alleging that an employee in a lower rated classification should have been paid at the higher rate when temporarily assigned to a higher rated classification.
The Collective Agreement provided:
23.02 When an employee is temporarily assigned to perform work in a classification inside or outside the bargaining unit paying a higher rate, he shall receive the rate for the higher classification. If a grid is in place, he/she shall be placed at the rate immediately above his/her current rate in the higher classification to which he/she was assigned.
In the Colonial Community Services case, a Residential Care Worker (“RCW”) came to work on the day shift in place of the Cook. She was paid her regular RCW rate of pay for that shift. A grievance was filed alleging that the grievor “worked in cook’s position ... [but] did not receive the cook’s wages”.
There was a practice in place in the workplace where a RCW replacing a cook would be paid at the RCW’s rate for the first two consecutive days of that replacement. If the replacement lasted longer than two days, the RCW would be paid at the Cook’s rate for the third and every following day in that sequence.
There were overlapping duties and responsibilities between the RCWs and the Cooks. According to the Arbitrator:
But where the tasks that are being performed in one position are the same as those performed in another, the question arises as to whether the parties to the collective agreement intended by such clauses that the employee who normally performs those duties for a lower rate of pay should be able to claim the higher pay rate of the classification into which he or she has been temporarily assigned
The Arbitrator summarized some of the principles
- performing duties that are found in both lower-paid and higher-paid job classification does not in itself entitle a grievor to claim the higher rate of pay; and
- the grievor performing duties in the higher-paid job must be carrying out the essential or core duties of that higher job classification: Re Fairview Nursing Home Inc and London and District Service Workers’ Union, Local 220 (1983), 9 LAC (3d) 342 (Rayner), cited in Ivaco Rolling Mills and USWA, Local 7940 (2002), 104 LAC (4th) 126 (Bendel).
Following a review of the job descriptions and the evidence, and while finding that the RCW replacing the Cook performs some tasks of the Cook, the Arbitrator nonetheless found that the grievor had not performed the “essential or core duties of the Cook when she filled in for the Cook”. In particular, the grievor was “ simply following the orders and duties that had been mapped out for her by the Cook when she created the menu.”
The Arbitrator also observed that the longer the RCW fills in for the Cook, the more likely that the essential and core duties of the Cook will have to be performed by the RCW. That being said, there was no need to decide that “tipping point” in this case.
Conclusion
The case is the most recent review of the age old question of when and under what circumstances should a lower paid employee be paid at the higher rate of pay when filling in temporarily for a higher rated position. The key principles are succinctly summarized and, since many collective agreements address this issue, a careful read of the case is called for both in interpreting the language and when drafting job descriptions.



