The 2021 federal budget introduced the underused housing tax which is basically a 1% tax on the value of non-resident, non-Canadian-owned real estate that is considered to be vacant or underused.
This tax was generally aimed at non-residents of Canada, however, there are situations where these rules can also apply to Canadian citizens or Canadian residents. Canadians may not be required to pay the tax but will have to file a return and claim the exemption. Note: there is a separate return that would normally be due on April 30th of every year. For the 2022 calendar year, CRA has extended the deadline to October 31st, 2023.
Please note, there are significant penalties for not filing these returns starting at $5,000 for individuals and $10,000 for corporations, per return, even if there are no taxes payable.