My tax concerns are essentially being unable to leverage the tax efficiency vehicles while working in the UK. i.e. having to pay tax in the US on income that attracts zero tax in the UK.
My actual concern is about going through the immigration system in future if I choose to rescind my green card. I understand that it isn't a pleasant experience I just wondered if it becomes any more challenging from having held an immigrant visa in the past.
> If you abandon your green card you'll have to pay capital gains on all your assets as if you sold them, I believe.
This is only true for certain holders with wealth over a certain amount, I wouldn't attract the exit tax.
It's more about being able to make good financial decisions if I am to stay in the UK as I'm uncertain at the moment. My plan was to study in the UK but given the situation (no access to the campus makes zero sense to me) I have a job in the UK now.
Engineers are paid what seems to be a significant amount less but there are many vehicles that optimize the taxes on that income. For example, tax free pension contributions are up to 40k/year (about $50k). You can also invest 20k per year of post-tax money in an ISA and pay zero tax on the earnings through interest and dividend. There are also tax allowances for interest on saving, captial gains allowance, entrepreneur's relief in addition to the personal income tax allowance. Stock options for employees are often very tax efficient too (10% tax). I think I worked out my total personal tax liability as about 19%.
So to be efficient with your money in the UK you need to leverage these vehicles. A 100k GBP London salary can be as efficient as a $170k Salary in SF, and that's before considering cost of living, co-pay on healthcare etc. If you have to pay tax on worldwide income in the US, it completely erases the savings these vehicles offer, so you end up with a tax bill equal to the difference between what you have paid in the UK and what you would have paid on the same income in the US.
Not to mention, companies that offer investment platforms for ISAs and SIPPs (do it yourself pension investment) will offer accounts to US residents due to the FACTA reporting overhead.