Source deductions are amounts legally required to be withheld from an employee's remuneration by the employer. These include federal and provincial/territorial income tax, Canada Pension Plan (CPP) contributions, and Employment Insurance (EI) premiums. The employer remits these amounts directly to the Canada Revenue Agency (CRA) on behalf of the employee. This process is fundamental to Canada's tax collection system, ensuring that tax and social security obligations are met throughout the year.

A. Voluntary deduction: These are amounts an employee authorizes an employer to withhold, such as for a pension plan or charitable donations, not a legal requirement for all.

C. Expense reimbursement: This is a non-taxable payment to an employee for business-related costs and is not a deduction from wages.

D. Net earnings adjustment: This is a general term for any modification to net pay and is not the specific term for legally required withholdings.

1. Canada Revenue Agency. (2023). T4001 Employers' Guide - Payroll Deductions and Remittances. Section: "Chapter 2 - Employer responsibilities and accounts", Subsection: "Your responsibilities".

2. National Payroll Institute. (2023). Payroll Fundamentals 1 Course Material. Module 1: The Payroll Function. (Content reflects CRA guidelines on mandatory deductions).

3. Canada Revenue Agency. (n.d.). Payroll. Retrieved from https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/payroll.html. The page outlines required deductions as "source deductions".