Canadians who move to the U.S. are no longer subject to tax on their worldwide income to Canada. A final Canadian tax return should be filed by April 30 in the year following departure. A Canadian may still need to file a Canadian return if he/she still has Canadian source income (employment, rential income, etc.).
On the U.S. side, once a Canadian has moved to the U.S., he/she is subject to tax on their worldwide income. A U.S. tax return (Form 1040) must be filed to the IRS by April 15 each year. It is important to note that the IRS has specific reporting requirements for those who maintain foreign assets in Canada.