A client asked “If I’m physically working in the US on a TN visa, but the company that paid me is in Canada, do I have to pay US tax? I made over $25,000 and was issued a US SSN”
The “NAFTA Professional visa” (TN) allows a citizen of Canada or Mexico to do specific work in the US on behalf of US employers. And because you were physically present in the US and made over $25,000, it is up for debate whether you qualify for the Canada-US Tax Treaty XV exemption.
You will likely be looking at filing a 1040NR return on your US-source income, and paying US tax on that. Canada-side you will file your Canadian T1 return, and claim US tax paid as a Foreign Tax Credit on your Canadian return.
Usual Disclaimer: This information is for general information purposes only, and deals with complicated and time-sensitive info that may not apply to your situation. Tax rules are always changing, and this information may not be current. Tax is complicated, this information is not tax advice, and don’t rely on this info to make tax decisions – Hire someone to help you.