Reply #172: Not really with Canada

[Oregone]

http://www.cra-arc.gc.ca/E/pub/tg/t4058/t4058-09e.pdf

Method 1 – Non-resident tax
Canadian financial institutions and other payers have to
withhold non-resident tax at a rate of 25% on certain types
of Canadian-source income that they pay or credit you as a
non-resident of Canada. The most common types of income
that could be subject to non-resident withholding tax
include:
■ dividends;
■ rental payments;
■ pension payments;
■ Old Age Security pension;
■ Canada Pension Plan or Quebec Pension Plan benefits;
■ retiring allowances;
■ registered retirement savings plan payments;
■ registered retirement income fund payments; and
■ annuity payments.

Method 2 – Tax on taxable income
Certain types of income you earn in Canada must be
reported on a Canadian income tax return. The most
common types of income include:
■ income from employment in Canada;
■ income from a business carried on in Canada;
■ taxable part of Canadian scholarships, fellowships,
bursaries, and research grants; and
■ taxable capital gains from disposing of taxable Canadian
property.
You may be entitled to claim certain deductions from
income to arrive at the taxable amount. You can also claim
a credit for any tax withheld at source or paid on this
income.

See, thats not about "world income" but income pertaining to activity in Canada (most of which should already be withheld, and therefore, you don't even need to report it).

The US is taxing "world income", even if its earned in another country and taxed by another country (exemption and deductions aside). Are they the *only* country that does it? No. But they are among the few. Ill look for a list.