Garcia v. The Queen, 2007 DTC 1593, 2007 TCC 548 (Informal Procedure) -- summary under Article 15

A bonus received in 2003 by the taxpayer when he was a resident of Canada was taxable in Canada, notwithstanding that the bonus was earned in 2002 when he may have been a resident only of the United States for Treaty purposes. The word "derived" meant "having its source", and the bonus was taxable at the time of receipt, regardless of when or where the employment to which it related was exercised.