As with most international tax planning, the key to cross-border Canada/US tax and estate tax planning is to synchronize the timing of the tax events and the taxpayer in order to minimize, and even eliminate, double taxation. Avoidance of tax in one jurisdiction may not be a satisfactory solution if it is merely a deferral or a shifting of a tax burden to a different taxpayer who or which may be subject ot tax at a lower rate (as well as a later time).
Canadian personal tax overview
Federal income tax is imposed on resident individuals, estates, trusts and companies based upon residency or domicile in Canada. Canada has an extensive array of dual tax treaties, so in many cases tax residency may be overidden by a treaty. If a resident, tax may be imposed on one's worldwide income, which, of course, is determined under specific definitions.