Taxland isn't like Wonderland, in case you're wondering. I mean, everyone there will make you feel completely mad, and nothing makes sense, and there's no explanation of anything, but...wait, how was I going to finish that sentence?
Anyway. About a million years ago (or four months, which is about the same in Internetland) I took a trip down to the US Embassy in London to attempt to get an ITIN number, or Individual Taxpayer Identification Number, from the IRS. This is necessary to prevent someone like me, who gets paid by a US company but isn't a US citizen or resident, being taxed both by the US and UK authorities. The US Embassy isn't half as grand as it sounds, by the way. Or maybe some of it is, but the IRS part is a boring little crowded office that could be anywhere from London to Texas. Except that in Texas they'd have air conditioning.
So what happens is you fill out a W-7 form (for detailed and helpful instructions have a look at Angela Stone and Alex Beecroft's excellent posts) and either take it or send it, with your passport and a letter from your publisher, to the US Embassy. Taking it is actually a more efficient way to get things done, as sending your passport through the post takes a looong time and is never 100% secure anyway. If you visit in person, the IRS man can also check over your form for you and tell you if you've made any mistakes. If everything is dandy, they then send off the form and a notorised copy of your passport to the IRS in Austin, Texas, to be processed.
For my blog with helpful hints on actually visiting the Embassy, have a look here.
Note: it really does help to visit in person, especially if you're quite good at pretending to be stupid. It's a skill I perfected years ago (quiet at the back), especially when dealing with financial type people and mechanics. Basically, anyone speaking a foreign language. They explain things extra slow if they think you're a bit dim. And don't forget to be polite. People who deal with stressed and confused people all day long rarely get much in the way of polite. So smile a bit, and they'll help you more. Yes, even those scary men outside with machineguns.
O'course, if you live a long way from Grosvenor Square and/or simply can't make your way to London you don't have to visit, but I'd really recommend you send your important documents as a recorded delivery, and make a copy of all your passport details just in case something does go wrong and you have to reapply for it.
Anyway. I did all this in May, and last week finally got my precious ITIN number in the post. This then gets sent to my US publishers, who use it to prove to the IRS that they don't need to take any tax off me at source.
Now all I've got to worry about is HMRC. Joy!