My son is from Manitoba and is going to university in Vancouver. Which province does he use for tax purposes?

It would depend. Normally you would select the province or territory where your son lived as of December 31, 2021. However, since he had residential ties in more than one province, you would select the province or territory where he has the most important residential ties.

Residential ties include where your home (owned or leased) and personal property are, and where your spouse or common-law partner or dependants reside. Other relevant ties may include social ties, driver's licence, bank accounts or credit cards, and provincial hospitalization insurance. For more information, see Income Tax Folio S5-F1-C1, Determining an Individual's Residence Status.