Hi all, I'll post a few things that might help you all out:
1. Regarding car, spend the $ to get a Canadian car otherwise you will get hassled by the border agents while entering Canada back saying you are a Canadian resident. Yes everyone knows that US has cheaper cars. As a "resident" you are expected to transfer your drivers license and get a car into that country. From your US license, its very simple to get a Canadian license, just make sure you have your drivers history. Also the US license does NOT get automatically cancelled, you may keep it active but are expected to only have one active. For a while, I had both a US and Canadian car and auto insurances in each countries because the border agents gave me such a hard time. This may not be kosher with the authorities.
2. Nexus is easy, get it. Takes a while. Make sure when you go to your interview that you can make your case. Apply online.
3. Daily commuters will eventually get recognized by border agents. It will make life simple. I-94s and CBSA travel histories may not reflect it, but the border agent will know you crossed yesterday and day before and so on.
4. You will have to file US taxes primarily. Claim it on your Canadian. Also remember to claim medicare/ss and other deductions. You don't have to pay double taxes. In my case in the last 7-8 years I double filed, it came out to be around $500-$1000 that I had to pay in Canada. Also claiming it will give you RRSP room for contribution. For simplicity, either don't contribute to 401k, or don't plan to bring it back anytime soon.
5. Regarding state taxes, best to either keep it at the border state you cross into, or at the office address. You don't need to cross every day if you don't have an office. But you can easily get a shared office space or regus meeting room and use it.
6. There are many many mail forwarding options. Better to just use mailrooms and pickup when locally there.
7. You can decline US health insurance. Get Canadian provincial health insurance.
8. Be ok with the fact that all of this may impact your green card application, if you care too much about that, don't move to Canada.
9. If you are planning to get Canadian citizenship, you will be heavily heavily scrutinized for all of this. It's not like the PR situation, someone will look at your file and question you about what good you are doing for Canada. If you don't really live in Canada, don't work in Canada, pay decent taxes etc. your case will be a lot weaker. For PR renewals, as long as you meet residency requirements, no one cares about the other aspects.
10. Border agents will often scrutinize you if you are away for extended periods. Even though CIC says 2/5 years as requirement, they will ask you a million questions if you are out for 6 months or 1 year. For them, anything more than 3-6 months is questionable. If you are extremely worried, take the Amtrak, the agents don't always check your travel history on it.
11. Getting to establish a Canadian credit history will be way harder than you think since you may have reportable income, but no employers who report to your credit file. Now if you want to buy a house, you may want to do so in Canada. So it becomes a Catch 22.
12. TD Canada and TD USA are not the same. They don't talk to each other. The only cross border bank that I have seen is HSBC, but they are a crappy bank to begin with.
Ok now, if you guys find a good tax accountant, let me know.