Hi Leo, It's a small world.
I was in a similar situation as you 25 years ago.
First what will your status be in the US, ie what visa?
Will you be leaving any money, savings or investments in the UK.If the answer is no your life will be much simpler as far as US tax goes.
I agree with LBYM!!!!!! It's the most important thing to do as you can't sensibly save or invest without it.
Read the wiki over at bogleheads.org about investing and start saving money in the US as soon as you can. Depending on your exact tax residency your US income and investment gains will probably not be liable to any UK tax. Here is a list of things to do. As you can do each one move to the next.
1) Save 6 months funds in a bank savings account.
2) contribute to any retirement accounts your employer provides, try to put in enough to get the maximum match from your employer after that try to max out your contributions
3) open an account with a mutual fund company like Vanguard or Fidelity or a discount broker like Charles Schwab and start investing money in equities and bonds etc....I'd start with index funds (they are the same as UK tracker funds)
4)With your mutual fund company open a ROTH account and put in as much as you can. This is a bit like an ISA, but it's meant for retirement.
Also remember to contact HMRC in the UK to see if you can make voluntary Class 2 NI payments as they are really inexpensive, about 2.50 pounds a week, and they go towards your qualification for UK basic state pension. If you are working in the US for a US employer you'll probably qualify.
Finally what are you doing for healthcare? If you settle in the US and are not ordinarily resident in the UK you won't be eligible for the NHS. Do you have US health insurance arranged?
OCCUPY ER, <=>
"The needs of the many outweigh the needs of the few, or the one." - Spock
Retired Mar 2014 at age 52
Target AA: 70% equity funds / 28% TIAA-Traditional/ 2% cash
Target WR: 0.0%,
Income from pension, rent, and eventually SS