How is payment for time taken off for union duties calculated if the union representative's pay normally varies depending on the work done?

Where a union representative's pay varies depending on the work done, payment for time taken off for union duties should be based on the average hourly earnings for the work that the representative does.

The employer should calculate the average hourly pay using the employee's own pay if possible. If it is not possible to calculate or estimate the employee's average pay, an average should be calculated based on the pay of employees in comparable employment (with the same employer). If this is not possible, the employer should calculate an average figure that is reasonable in the circumstances.

The calculation should include any bonuses, commission or performance-related pay to which the union representative is entitled. Further, when setting bonus or commission targets, the employer should factor in that the employee will need time off to undertake union duties.