Thanks for asking your question! I'm sorry to hear about your tax issue and I'm going to try my best to help you understand or resolve it.
How are you today?
Currently, there's no way to "rollover" your retirement assets from an American plan into a UK plan, so you would still have the US plan to draw from during your retirement years
But when I start drawing from it once I'm retired, will I be subject to US tax and/or UK tax?
You would follow all the same rules, such as being able to draw at age 59.5
It's taxed in your country of residence, which would be UK under article 18
Is the amount I draw then treated like income from a UK tax perspective
That is correct, but you would not be taxed on it in the US
That's great. That's what I wanted to know. Many thanks
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Presumably the same applies to my US company pension plan. (not that it's very much!)
Yes, that would be the same treatment