Fees subject to taxes are annual
union or professional dues that included GST/HST or QST. Fees not subject to
taxes did not include GST/HST or QST. You would have to look the receipt provided
to you to see if sales tax was included or not. You can also confirm with the
organization you paid the dues to.
If you had your dues already
included on a T4 slips (box 44), then you only need to enter them on the T4 and
nowhere else. Putting them on the “Union or Professional Membership Fees” as
well would cause the amount to double.