I cashed in my 401k before I left so I have no idea how to report that.
Your 401k administrator will send you a 1099-R that shows the amount you received. You'll have to pay a 10% penalty and tax on the amount. The commercial tax software packages will prompt you to enter the amounts from the 1099-R so the in the correct places on the 1040.
I know I would file married separately and I don't need to submit a fbar because I am well under the limit. For future tax years I think I need to file a form about being away for the year, can you tell me which one that is? I don't think I need that this year because I've only just moved in May 31 2013. My mom was on the phone with the IRS for an hour trying to get information but they said to refer to the website. In general what forms would I need to file for the next tax year when I have been in the uk all year?
Any guidance would be really welcome. I'm sure these are terribly dumb questions but if you have any free time to provide some pointers I would really appreciate it! Thank you
You have to file the same forms and maybe a few extra to deal with foreign earnings.
There are two ways to avoid double taxation on your UK wages. You can either claim a tax credit on your US taxes for UK taxes paid using Form 1116 or exclude the UK earned income from you US taxes using the Foreign Earned Income Exclusion (FEIE) and Form 2555 or 2555-EZ.
Remember the US taxes US citizens on their worldwide income so that includes everything, UK bank interest, dividends etc etc. as well as your UK salary.