There is no problem as a UK citizen, as has been mentioned you just get an ITIN number. You CANT get it before you actually have winnings, as was previously the case.

Pretty much all of the casinos are registered agents, and can get you the ITIN. I got mine first years ago at the Mirage, after winning a SNG. They give you a couple of simple forms to fill out, and then pay you the whole winnings. (Carry your passport with you at all times!) A couple of days later you go in and they give you the number. I keep mine on a sticky in my passport, and like to shout loudly, I don't pay no stinkin' taxes!

No problem at all, don't worry about it until you win something worth worrying about, and when you do, its simple.

Of course, what I'm absolutely suggesting that you don't do is take advantage of the situation, now that you're in a situation where everyone else on a final table is paying30% in taxes, you could offer your services to come 1st on the paper work, in exchange for an extra 10% for example. Of course though, I'm am clearly suggesting that you do not do anything like that. Really.

True, but there is a difference between reporting large cash transactions for Homeland Security tracking and cash outs/winnings reported to the IRS. Just because you have a large cash transaction does not necessarily mean that you have gambling winnings reported to the IRS.

There are three concepts here which are being conflated.

(1) Will I be taxed on my winnings? This is governed by a bunch of different laws, from international law to federal law to state law. I wouldn't take tax advice from the Internet, unless the giver of advice was an expert in tax law for the region I am interested in. For residents of the United States, you are most certainly obliged to report all your net winnings, even if you won $15 at the slot machine. It's self-reported for US tax filers.

(2) Will I have my winnings withheld? This is a fundamentally different question than (1) and whether you have winnings withheld may be independent of your actual tax liability. In general, winnings are withheld so that people are more honest about self-reporting gambling winnings; if you're a US tax filer and win above a certain amount (which varies by game and location), you get a W2-G and possibly winnings withheld. If, in the end, you don't need to pay taxes (e.g. you lose a ton of money and are a net loser), you get the withheld money back. No, it's not fair that the government holds your money for a year - that's just the way it works. If, in the end, you do need to pay taxes and you didn't have money withheld, you need to pay up. So all four scenarios are possible - you pay but don't have to, you pay but have to, you don't pay but don't have to, and you don't pay but have to.

(3) Will the casino notify the government if I move a lot of cash around? This is totally unrelated to the first two questions. The filing is called a CTR - Cash Transaction Report. It just states that you cashed in/out more than $10,000. It neither means you won nor lost, nor does it mean you owe or don't owe taxes. It's just a way of tracking large blocks of cash.

As a side note, if you repeatedly cash out sums under $10,000 in an effort to evade a CTR, that's also a crime. I believe it's called a SAR (Suspicious Activity Report) but casinos are also required to file those (without your consent) if they think someone is trying to avoid a CTR. There's absolutely no reason why you should fear a CTR unless your cash was raised illegally.

Very good post, and here's 3a:

Casinos these days will also be asking for ID or a players card if you're cashing out several thousands dollars (every casino will have their own #) to prevent you from structuring (what you describe above). So the point is to not be alarmed if you walk up to the cage with four yellow chips and they ask for ID- it's for the Justice Dept, not the IRS.

Lol I was kept waiting for 10 minutes at casino royale, trying to cash out the huge sum of $525!

Casino Royale? They probably had to go down to the vault to find $525

I've had kindof the opposite effort suggested. During a break the TD wandered up and said "if you could convince these guys to do a deal before we get to the reporting limits, I'd sure appreciate it so I don't have to do ITIN's and withholding for the foreigners."

Even at that, Harrah's was doing it wrong. They're supposed to report the NET win. I cashed in a Caesars tourney for $680, but I paid $120 entry plus $100 add-on. Not only did they incorrectly give me a 1099, but they put the full $680 amount on it.

Which is why I did not mention the IRS or taxes in my post.

Not an expert in anyway, but have practical
experience from beginning of this year when I
cashed in one of the Bellagio tourneys (under
5k cash). I had to fill out some simple paperwork
and the casino acts as an registration agent to
get you your ITIN, and they then pay you in full.
You can then use this ITIN number also for any
future cashes (you can pick up the number a few
days later, and you'll get an official letter from
the IRS later as well).

I guess it's relevant to know I'm also a UK tax
payer (or in this case non-payer), but not a UK
citizen.

This to my understanding is pretty much how it works
in most of the casinos these days, as it is actually
impossible to get an ITIN number ahead of time
"just in case" you win something.

Sorry if this looks messy, using my mobile to write.