Tried to skim through all existing questions, but couldn't find a match to my situation - so any help or input appreciated.
I'm looking at a possible scenario where I'm on the Canadian payroll (with all standard deductions like Canada pension plan, RRSP etc) of a company (US based company, but also has significant presence in Canada) - but have to work every Monday to Friday in US offices (for a unknown long term - not a short 3 month assignment or something). I am a Canadian citizen myself and intend to keep my house (and family) in Canada.
Taxes: I presume all the regular Canadian taxes etc has to be done, will I end up filing US taxes as well (because of the significant presence clause and the company has to report that?). I'm OK with filing the dual taxes, but is there any complication as I am actually employed by the Canadian arm.
Visa: I am currently a NEXUS holder and travel on B1 when I go to US (for meetings, conferences etc). In this case, since I am regularly working in the US office - do I need a TN visa? Or since I am on the Canadian payroll and since I do not actually have an employment offer from a US company, it is not required?