Do I have to file a T1135 if I own a vacation property outside Canada in Ontario?

Not necessarily: you file Form T1135 only if you own specified foreign property costing more than $100,000 at any time in the year. The threshold is based on cost amount, generally the adjusted cost base, not market value.

A vacation home used mainly as a personal residence is personal-use property and is not specified foreign property. The CRA's Florida condo example shows the line: a condo used only as a vacation home is not reported, but the same condo rented for eight months with a reasonable expectation of profit must be reported. Part-year rental only to recover expenses, with no expectation of profit, is treated as personal use.

The form is due on the same date as your income tax return, which is April 30 for most individuals. The penalty for failing to file is $25 per day for up to 100 days, with a minimum of $100 and a maximum of $2,500, and larger penalties apply to knowing or grossly negligent failures. Even below the threshold, you must still report income from foreign property.