The CRA form used to adjust payroll income tax withholdings at source for employees who earn commission income and have commission expenses is Form TD1X – Statement of Commission Income and Expenses for Payroll Tax Deductions. The CRA explains that an employee completes TD1X if they receive commission income (or salary plus commission) and want the employer to adjust tax deductions to take commission expenses into account.

This is different from:

TD1, which is the Personal Tax Credits Return used to claim basic/personal credits and determine standard withholding (not commission-expense adjustments).

T777, which is used to claim employment expenses on the employee’s personal tax return (not to reduce payroll withholding at source).

TP-1015.R.13.1-V, which is a Quebec form used to request a reduction of Quebec income tax withholding in specific situations (not the CRA commission-expense at-source form).

Operationally, payroll should keep the TD1X on file and apply it to income tax withholding calculations until the employee updates or replaces it.