Serbinski Accounting Firms

Does your spouse identify that she is married on her Cdn return, and does she report your US income on page one, for determining benefits?

I would opine that because you spend more time in canada than US, AND that your family lives in Canada, with whom you live, particularly since you do this year-after-year, you would be considered a resident of Canada, by the treaty tie-breakers.

You can keep your TFSA with most brokerages, although there is little benefit for doing so while in US.

Your investment account cannot be managed while in US, as this violates SEC regulations, because Cdn brokerages cannot deal with US residents in non-sheltered accounts.
You are best off ...

It would be better if you could fix it, as it is impacting the performance of your IRA.

However, simply keep track of the Cdn tax withheld, and include it on your Cdn tax return along with any other withholding, so it isn't "lost".

I use 8833 to explain any treaty position I take, regardless of whether it is mandatory or not, and do not list any specific IRS code. Just keeps them from guessing.

Since you said we've discussed these issues before, I''ll leave it as that.

If you change the use of your former principal residence to a rental at some point after your move, you would only be able to step up the ACB for IRS purposes, if you also filed for change of use in Canada. Otherwise you have not met the requirement of XIII(7), in that there would be no "deemed ...

As you probably know, the withholding tax is imposed by, and paid to, Canada, not US.
Without the treaty, the tax would be 25%.
At a minimum, if you refer to Article X.2(b) of the treaty, this should reduce the withholding to 15%.
For Cdn stocks held in an IRA or other retirement account, that ...

As you are aware, your TFSA, from a taxable account point of view is simply an investment account in the eyes of IRS, so the income you report arising from a withdrawal would simply be any gain/loss from the sale of the particular investment(s).

Not too sure about the 3520, as I chose to not view ...

Yes.

RRSPs are pension income. Pension income is General.

There is absolutely NO requirement for the 401(k) income to be periodic, in order to be split.

From an FTC point of view, US pensions are not subject to the 15% limit, and the early withdrawal penalty IS allowable along with the regular tax, even if this pushes you above 15%. This has been accepted by CRA for well over a decade. This was the resolution when many began "transferring" their IRA ...

She can sell from anywhere in the world.

There is no reporting of annual "internal" income, only withdrawals.

The treaty says nothing about FBAR, 8938, and so on. so one needs to know the requirements of each form, and how all of their accounts under their control is valued, and structured.