I am also a Canadian living in the US and have filed the paperwork needed to exempt my RRSPs from US Federal tax liability. But my 'keen' tax preparer recently found out that there is no such tax treaty between the individual states and Canada. Therefore, depending on the State you live in, you could have state tax liability on your RRSPs. And so I now pay California state taxes on my RRSP interest, capital gains (whether realized or not) and dividends (even automatically reinvested dividends).

I sure as ____ won't retire in CA. Though instead of getting back the 30% premium it cost me (in Cdn-US exchange) to move here 15 years ago, it may cost me that again to move back to Canada, the way the US gov't is trashing the US$ (not to mention loss in my house value here).