If your residency is changing, it may affect how you're taxed. Canada, for instance, has many residents that spend half the year in warmer parts of the U.S. "One of the issues there is when you're considered a resident of most countries in the world, you have to file taxes there," said Julia Chung. "We have a lot of Canadian residents who are just finding out that they're supposed to file a tax return with the U.S. every year."