I have shares acquired through an American company I was working for. They were purchased through the company ESPP plan. I was living and being paid in Europe at the time ( I am not a US citizen). 10 years later I have moved to the US full time and will be shortly selling these shares. Am I liable for US ordinary income tax on these shares, even though they were acquired while not a US tax payer?
Am I liable for US ordinary income tax on these shares, even though they were acquired while not a US tax payer?
No, you're not liable for the US ordinary income tax.
If you are a US tax resident already, you are liable for the US capital gains tax.
Since the holding period was more than 1 year, that means preferential tax rates, but you're still going to pay taxes on your gains on these stocks even though they were acquired when you weren't a US tax resident. To avoid that, you should have discarded them before moving (and maybe bought back if you wanted to continue holding them).