When is the Underused Housing Tax return due and how do I file it?

The Underused Housing Tax return for a given calendar year is due by an annual deadline set by the federal government, similar in structure to how other federal tax filings work, but the specific date has been subject to administrative extensions in past years, so it should be confirmed directly with the Canada Revenue Agency for the tax year that actually applies to you rather than assumed from something you may have heard previously. Missing the correct current deadline is exactly the kind of mistake that triggers the penalties covered in a related question.

Filing is done using the CRA's designated Underused Housing Tax return, generally identifying the specific property and the owner's details, and is typically completed through the same broad channels used for other federal tax filings, whether that means working with an accountant familiar with this return or filing directly with the CRA depending on your comfort level with the form.

Because the return itself, the deadline, and the exemptions available all interact in ways that are easy to get wrong, get help from a tax advisor familiar with this specific return, especially if your ownership involves a corporation, trust, or non-resident status.