As an American residing outside the US with a spouse who is not a US citizen I have always chosen Married Filing Separately for my filing status. The intent was to shield any income and assets she has from taxation by the US.
Now with a child who is registered as a US citizen I qualify to file as Head of Household with the IRS for my US taxes. This year I came across an H&R Block article which seems to imply the best treatment would come from applying for an ITIN for my wife.
In particular the following paragraph caught my attention:
Choosing ‘Head of Household’ status will also allow you to claim the spousal exemption if your spouse does not have any U.S. income and he or she acquires an ITIN, as discussed above. This is the most beneficial status you can choose without subjecting your spouse’s income to U.S. taxation. Neither this nor the aforementioned filing statuses invite any type of U.S. tax liability on your spouse.
If my wife were to receive an ITIN will she forever be obligated to file (or for me to include her in my filing) with the IRS?
This mentions income which I generically assume to be salary from working. But what if she has investments, will those be protected from a US tax liability too?
Are there any long term disadvantages or caveats I should consider before applying for an ITIN for my wife? I don't want to have a short term gain of claiming a spousal exemption only to find I'll pay for it down the road in some other way.