Posted: Thu Jul 10, 2008 10:20 am-
The entire purpose of TN-1 is to allow people to enter the US temporarily to work, plenty of people have them who only work a few days or weeks a year in the US. Just because a lot of people stay the full year doesn't mean you have to.
Frankly the longer you spend outside the US the easier it should be to get TN-1 status as you clearly have "bona fide non-immigrant intent".
Read this tax publication:
http://www.cra-arc.gc.ca/E/pub/tg/p151/README.html
Clearly you are a resident of Canada so you pay tax in Canada. Any income you receive from US sources you must claim a foreign tax credit on (as explained in the general guide for the T1) to avoid dual-taxation.
For any US source income you file Form 1040NR with the IRS as well as Form 8840 to claim the tax treaty exemption, as it outlines in that CRA publication.
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Steve.