Hi, as Delphision mention, CRA should have a record on file for you that you submitted a T1213 form, and that it must be approved. You should have received a letter from CRA stating that yes, reduced tax withholding on your severance is approved, and I hope you gave a copy to your payroll. Should you have any further concerns, you are free to call CRA at 1-800-959-8281 to check things out. Your severance payment is straight cash on your tax return to report on line 130, but then you get the RRSP deduction. This gives you a nice break. Did you get a tax slip for your severance payment? Form T4A slip is issued a lot for lump sum amount, in that situation you could report the income tax withholding, had you have any. This is one question you ask to CRA.
