You made an error in calculating deductions
You may find that you have over- or under-deducted EI, CPP, or income tax. As soon as you learn that the required amount was not deducted, contact your employee.
This type of situation is not considered remitting errors. To fix a deduction error or a salary overpayment:
- If you have not filed the information return, refer to: Make corrections before filing
- If you already filed the information return, refer to: Make corrections after filing
Source: Government of Canada