Can an Ontario employer require salaried employees to work unlimited hours without extra pay?

No, not simply because the employee is paid a salary. Being paid a fixed salary rather than an hourly wage doesn't, on its own, remove an employee's entitlement to overtime pay or protections around hours of work under the Employment Standards Act, 2000. Whether overtime applies depends on whether the employee's actual duties fall within one of the Act's specific exemption categories, such as certain managerial or supervisory roles genuinely performing that function, not on how they're paid or what their job title says.

This is one of the most common and costly misunderstandings employers have. Labelling someone a "manager" or paying them a salary "in lieu of overtime" doesn't make an exemption apply if the person's actual day-to-day work doesn't meet the substance of the relevant exemption. An employee who is nominally salaried and titled as a supervisor, but who spends most of their time doing the same hands-on work as the staff they supposedly supervise, may well still be entitled to overtime pay.

Because misclassifying employees as exempt is a frequent source of significant back-pay claims, employers should assess exemptions based on actual duties, ideally with legal advice, rather than assuming salary alone settles the question.