Thanks Stu. I'm conversant with the 6 months limit on entry, which applies to all visitors, not just Canadians. There are (legal) ways to extend the 6 months limit, specifically by filing Form I-539, and this has been used by some folks visiting here, e.g. Mick and Pat from the UK - see
this discussion. My understanding is that this wouldn't help Canadians because it could affect their Medicare benefits and their pension, although the length of time apparently varies by province.
... a 'B' class visa is issued only for 180 days or so. A 'B' class visa is a verbally issued visa granted by the US Immigration Officer when he admits a visitor to USA.
It was my understanding that Canadians do not require a B1 or B2 visa to enter the US for a stay of up to 6 months. For visitors from other countries, a B1/B2 visa is issued by a US Consulate (or Embassy) outside the US, is stamped in their passport, and is often valid for 10 years. But the length of any given stay for anyone with or without a B1 or B2 visa is determined by the Border Patrol Officer at the port of entry; This usually won't be for longer than 6 months (90 days max for someone using the
Visa waiver program). The time restriction will be entered on a Form I-94 that is stapled to a page of the passport.
Meanwhile, the second part of the brain fart cleared ....
Visitors to the US staying here more than 182 days could be considered to be resident, and thus subject to US income tax. Some classes of visitors are supposed to obtain a
Sailing Permit (Form 2063, tax clearance) from the IRS before leaving, but this is not usually applicable to tourist visitors or anyone not having a source of income in the US.
Steve Pally, a Canadian citizen and annual snowbird, wrote a lengthy message on the subject of US tax implications for visitors to the US
here and it was subsequently put in a forum library article
here.