Info on the T1198 form:
(As found on the CRA website)
Qualifying retroactive lump-sum payments
Certain retroactive lump-sum payments totaling $3,000 or more (not including interest) are eligible for a special tax calculation when an individual files their income and benefit return, regardless of the amount of tax you withhold from the payment.
To qualify for a special tax calculation, the payments described on Form T1198, Statement of Qualifying Retroactive Lump-Sum Payment, must have been paid to an individual for one or more preceding years throughout which the individual was a resident of Canada. The payments must have been paid after 1994 and relate to years 1978 and later.
Eligible sources of income are:
income from an office or employment received under the terms of an order or judgment of a competent tribunal, an arbitration award, or an agreement to terminate a legal proceeding (including amounts received as damages)
wage-loss replacement benefits
Notes
An amount paid under normal collective bargaining, such as negotiated back pay, is not a qualifying amount.
A different tax treatment may apply if the employee is deceased. In such a situation, call 1-800-959-5525.
The payer has to fill out Form T1198 or provide the following information in writing to the employee:
the year in which the lump-sum payment was made to the employee
a complete description of the lump-sum payment and the circumstances that required it to be paid
the total amount of the lump-sum payment, including a breakdown between the principal and the interest element, if any, of the payment
the principal amount of the lump-sum payment that relates to the current year and each of the preceding years covered by the payment
The employee has to send Form T1198 to their tax centre and request the special tax calculation be applied to their income tax and benefit return.
CPP contributions, EI premiums, and income tax
Deduct CPP, EI, and income tax from lump-sum payments that are income from an office or employment. Calculate these deductions using the instructions under Bonuses, retroactive pay increases or irregular amounts.
Forms and publications
Brandi Hughes - Grievance Officer CUPW Local 824
306.281.5330