One of the largest groups is retirees in Canada. Finding an accountant to do both US and Canada taxes is both difficult and expensive (over $2000/year), so the

One of the largest groups is retirees in Canada. Finding an accountant to do both US and Canada taxes is both difficult and expensive (over $2000/year), so they want to renounce ASAP. Also there's huge legal jeopardy for undeclared foreign retirement accounts.