Here are some thoughts/tips that I've learned since I got here and that might make other people's lives easier if they are planning a similar move. I will probably update this post as other stuff comes up - and if anything is factually incorrect, please let me know.
1. Social Security numbers. A SSN is the key to much of life in the USA. Everyone expects you to have one and if you don't it can cause problems. Tom is on an H1B visa and unfortunately when the application was made the box that gets you one before you arrive wasn't ticked. If you're applying - make sure that it is ticked. It will save a lot of time and hassle later. For example, technically you are supposed to apply for a driving license within 10 days of becoming resident in California but you need a SSN to do so and Tom didn't get one for at least 3 weeks. This hasn't been a problem but it's an example. Also you can't open a bank account easily here unless you have one. If like me you're not allowed one, you need to know that this will limit some things for you. Which brings me to
2. Banking. Think about this before you get here. We managed to open an American account through HSBC before we arrived which has made life much much easier. Banks here will want some proof of income, credit history (which you won't have) as well as an SSN which you may not have. If you're not going to get an SSN there's a chance that the bank won't let you have your own account. Banks also charge for bank accounts even when you are in credit and that includes paying to buy cheque books. That is unless you have a premium account which will rely on your having plenty of funds in the account. And while we're at it, ATMs charge you at least $2.50 for each withdrawal if you don't bank with them. There's no agreement between the banks allowing free withdrawals like there is in the UK. This is one of the downsides of banking with HSBC as they are not very common over here. It is outweighed by the fact that we easily got the account sorted but it is an everyday pain.
3. Lack of credit history. Bring money. And bring paperwork for things like savings accounts, mortgage payments. But even with the latter you will still have no credit history. I am not sure how this works in the UK for a new resident but I'm pretty sure that the power companies don't sting you for a massive deposit. We have paid a deposit of over $500 dollars for that account. We have also paid over $750 deposit for our mobile phone account. We also had to pay an extra month's rent as deposit - so two month's rent as deposit not the standard one - despite providing lots of proof we were reliable including references from our previous landlord and mortgage statements. This will give us a nice little lump sum back into our accounts in a year's time but at the time, we had to find the cash. I realise that many of you will have your moving expenses paid for and even the move organised - we certainly had help. But having ready access to money is important and makes life much much easier. The lack of a credit history will also have an impact on your credit limit on any credit card. Ours isn't very high (about 25% what we had access to in the UK) currently for that reason and sometimes (like when buying a flat's worth of furniture) we've had to use other accounts to get the bill paid.
4. Medical stuff. If you have kids bring what medical records you can for them. In the UK this means making sure their little red book (how very Maoist of the NHS!) is up to date particularly with regard to immunizations. If you are sending your children to public school in the US (i.e. state) then they require a medical form to be completed by a US doctor and proof that the child has had the required immunizations. I don't know what rules there are if you're going private but bring the records anyway.
5. See a tax expert soon. The US doesn't do PAYE, or at least not in the way we know it. You are responsible for your tax and declare to your employer what deductions/allowances you are going to claim so they can adjust your salary each month. So in the sense that tax is deducted each month from your salary it is the same. But trust me, you need someone who understands this stuff to explain it to you, so that you claim for the right amount and don't end up over- or under-paying. You will also probably need an accountant at the end of the year. Oh, and while we're at it, make sure you bring your UK income and tax records with you as you are required to declare it even though you weren't resident yet in the US - leastways that's what we've been told. I.e. we arrived at the start of November so have 10 UK based months to account for first and then the 2 US months. It won't mean extra tax but it still has to be accounted for. Confused? Get an accountant. We certainly are.
That's all for now.
An addition which is quite specific.
Driving. We're signing up for Zipcars which is a car share scheme. They require a copy of our driving record and I wish I had obtained this before I left because it would have saved me the 1 am call to the DVLA this morning. They are only open 9-12. Still they were very nice about.