Income that has been earned by you during 2021 should be entered on your T4 even if you have union/membership dues.
According to TurboTax, "Box number 44 in T4 slip is only for union dues that are shown in T4 slip received by you from your employer. Do not enter union dues shown on other receipts here. You'll be prompted to enter this information later in the interview".
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There is also another way to enter the number of union dues.
First of all, please click on the "find" option which can be seen on the upper side of the screen.
Enterunionand select Go
Enter your amounts and select Continue
For more information on the T4 slip please visit the link below: -