Offer your thoughts or opinion on the input financial query or topic using your financial background.

ESPP taxes after relocating from Europe to the United States?
I would suggest to get an authoritative response from a CPA. In any case it would be for your own benefit to have at least the first couple of years of tax returns prepared by a professional. However, from my own personal experience, in your situation the income should not be regarded as "US income" but rather income in your home country. Thus it should not appear on the US tax forms because you were not resident when you had it, it was given to you by your employer (which is X(Europe), not X(USA)), and you should have paid local taxes in your home country on it.