Helpful Guide to the Legal Requirement of Proper Notice From a Resigning Employee
It commonly understood that when an employer that fails to provide proper notice of termination of employment (or pay-in-lieu of notice) such constitutes as a wrongful dismissal; however, less known is the requirement that an employee also has a duty to provide proper notice. Perhaps the proper notice of employment resignation is less known as such arises in the common law only and is without mention within the Employment Standards Act, 2000, S.O. 2000, Chapter 41 ("ESA") and thus laypeople, and perhaps even many lawpeople, fail to recognize that a mere lack of codification within the employment statute fails to negate the requirement.
Notice Period, required from employee
Whereas the ESA is silent on the notice requirements of an employee, and if the employment contract was also silent, such leaves the question as to what period of notice is therefore required from an employee. Similar to situations where the notice period requirement imposed upon an employer is of 'reasonableness', the same applies per the case Gagnon & Associates Inc. et. al. v. Jesso et. al., 2016 ONSC 209 where it is said:
 It is a well-established principle that an employee is obliged by law to give reasonable notice of the termination of his employment to his employer. [see Lazarowicz v. Orenda Engines Ltd. (1961) 1960 CanLII 151 (ON CA), O.R. 141 (Ont. C.A.) and Oxman v. Dustbane Enterprises Ltd.,  O.J. No. 2067 (Ont. C.A.)].
 Jesso effectively gave no notice. Although he offered to remain for two weeks conditional upon GA’s agreement of monies owed to him, he indicated that during that two week period he would not undertake any new work.
 The notice required of an employee will be a function of that employee’s position with the employer and the time it would reasonably take the employer to replace the employee or otherwise take steps to adjust to the loss.
This mandate requiring reasonable notice was also stated by the Court of Appeal within the significant case of GasTOPS Ltd. v. Forsyth, 2012 ONCA 134 wherein a notice of two weeks provided by the employee was deemed "totally inadequate" whereas such would leave the employer unable to fulfill existing contracts as well as unable to continue the cultivation of additional business opportunities. Specifically, the Court of Appeal stated:
 The trial judge found that the notice the personal appellants gave was totally inadequate, that each of them knew it, and that they intended destroy GasTOPS’ technology business. They were fully aware that these departures would leave the respondent unable to fulfill its existing contracts, or continue to pursue the business opportunities it had been cultivating.
In circumstances where an employee fails to provide proper notice the manner of determining damages is based on the loss to the employer that arises from the failure to provide notice rather than arising due to the overall departure of the employee as was said by the Court of Appeal in the case of Bradley v. Carleton Electric Ltd., 1998 CanLII 7140:
 The key employee in Carleton Electric Limited’s utility division, Bradley, after working for Carleton for 18 months, quit on short notice. Bradley and Carleton sued one another in breach of contract. The trial judge found that Bradley should have given Carleton three months’ notice that he was leaving and awarded Carleton $10,000 plus costs.
 All that Carleton was entitled to from Bradley was reasonable notice. The measure of damages was not therefore the cost of Carleton as a result of Bradley leaving the company, but the cost of Carleton as a result of Bradley’s failure to give notice.
 In our opinion, the trial judge did not err in his assessment of the damages and we would dismiss the appeal with costs to the respondent.
Perhaps for security reasons, among other things, receiving notice from a resigning employee usually results in waiver of the notice by the employer (and thus the pay-in-lieu obligations of the employer becoming due); however, where the employer is injured by the failure of notice from the employee, the employer may deserve compensation for damages arising from the failure of notice. As to how to calculate what would be reasonable within a particular situation, such appears very difficult to predict and will be governed by the circumstances involved within each unique case.