England - Tax at 10% is within the 'buy-in'.

Tax on 'live betting' was abolished maybe 10 years ago.

There is still tax of 10% on all 'off-course' betting but you have a choice - pay the tax on your stake and your winnings are tax free - dont pay it and the tax will be deducted on the full return (winnings & stake) before you are paid.

If, however. I place a bet within the UK for a horserace within the US there is no tax.

My highest single win in NV was $2300. I was not required to fill out any paperwork. I have had to fill out money laundering paperwork for cash withdrawals/purchases over $10,000 though - I guess that applies to everyone?