Maintaining part time UK employment when moving to US

I work in a UK university, and it's common when staff leave that they keep a small fractional position to maintain the affiliation, at least for a year or two until outstanding students finish etc.

How does this work when moving internationally? If I got a position in the US and move my residence there, but kept say a 0.2 FTE (1 day a week) at a UK university, what are some issues I should be aware of?

The simplest would be just to keep a UK address, but then UK tax would be deducted. I guess I wouldn't be able to offset that with FTC because I shouldn't actually pay it if I am not tax resident in the UK. In such a situation I would probably divert all the UK income directly into the USS pension - this might avoid the UK taxation issue, but tax would then be due in US on that income with no FTC to offset (although I could refile and have FTC carried forward from the last few years to cover this?)

Any thoughts on other things I should be thinking about for this potential situation? Thanks for any help and advice.

I don’t know if paid employment from the UK is different from receiving a UK private pension but when I was resident in the USA and receiving a UK private pension no taxes were paid to HMRC. I had to complete a form to show that I was no longer UK tax resident to get a nil tax code.

Maybe you could file an R43 if the income was low enough. Otherwise you may fail foul of the SRT’s.

When you move to the USA, the US becomes the primary taxing authority. This means that a UK university would have to pay you as a US employee and not a UK employee. They are unlikely to be willing or able to do this. One solution would be to get an honarary appointment in the UK which enables you to maintain your UK academic status without pay. The UK university could pay you expenses and perhaps as a consultant (on which you would pay US tax). There is also an article in the US-UK tax treaty that deals with academics. A US academic can work for a short period at a UK university. The pay is not subject to UK tax but US tax (which you would need to take care of).