I took a continuing competency course for work that was not mandatory. Can I claim this cost?

You can deduct the cost of a training course as an employment expense. The course has to maintain, upgrade, or update your existing skills or qualifications that relate to your employment.

To learn more, visit: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-return/completing-a-tax-return/deductions-credits-expenses/line-22900-other-employment-expenses/commission-employees/training-costs.html