It is even worse for US Persons in Canada, many of whom have never even been a US resident in their entire life. The reason is our tax treaty... If you file in Canada, you&#x27;re good. At least that is how it was. Now they are going after these people because capital gains are exempted from this aspect of the treaty so they think they are compliant by having filed in Canada, but then find out a house the sold 10-20 years ago should have been declared even if they have never had to file US taxes before.