If you have overdeducted or underdeducted EI, see EI overpayment and recovering EI premiums.

If you have overdeducted or underdeducted CPP, see CPP overpayment and recovering CPP contributions.

If you have overdeducted or underdeducted income tax and realize it in the current year, you can make an adjustment on a subsequent pay. However, if you realize the mistake in the following year, do not adjust the T4. The adjustment will be done when the employee files his or her tax return.

Once you file your information returns, we verify that the required deductions match the one you have reported. If we find inconsistencies, we send you a list for you to explain the differences. For more information on this process, see Pensionable and insurable earnings review (PIER).