On: Linus Torvalds became US citizen

[tokenadult]

Yes, United States citizens are liable for taxation on their worldwide income (unless there is a tax treaty between the United States and the other country in question).

[volkadav → tokenadult]

Only over some threshold (iirc, though it has been some time, around 80k USD equivalent). So maybe yes for someone with a comparatively high income, but not so much a worry for a reasonably large segment of the population. Naturally if this happens to apply to anyone reading I would urge consulting a professional for current advice. ;)

[ojbyrne → tokenadult]

The US has tax treaties with most developed countries, including Finland.

[dtegart → tokenadult]

You still need to file tax returns, even if you are under the limit to prove that you owe no tax.