From the information given:
The US citizen is living with her Canadian citizen husband in Canada; where he works and earns a Canadian income. How is that any of the US Federal Government’s business?
They are not using the US highways, medical facilities, or any other Gubmint funded benefits. If they have monies invested in a US bank - how does that cost the US Treasury? That would be a good thing.
Never mind that it makes U.S. corporations offshore their operations, or this woman renounce her citizenship . . . to make an omelette, you have to break a few eggs.
Because the IRS now has the legal right ( if a country signs the IGA) to look into the foreign spouse’s bank account to see if the American is hiding anything.
Google United States Norway IGA bank agreement. Its 36 pages of pure government overreach. Will make Communists envious.
That was a couple of decades ago. This is coming to a head now but it has been a surreal situation for years.
“The US citizen is living with her Canadian citizen husband in Canada; where he works and earns a Canadian income. How is that any of the US Federal Governments business?”
Seems like legally as long as he has a bank account in his name only, the IRS is not entitled to any information about the account.