<prompt> Human: Lets say my income tax is 28. According to bonuses are subject to a supplemental tax of 25. This sounds like it is in addition to my regular income tax. So, if I receive a 1000 bonus, will my payout be 10001 - 0.25 or 10001- 0.251 - 0.28?  <response>: I think you are looking at withholding -- a flat 25 is sent to treasury. Its like withholding that happens from paychecks ... its a provisional payment of tax.At tax time, you add up your income and bonus together. You calculate your taxes based on your taxable income.Then you just look at tax - total withholding. If thats positive, you still owe a little. If total withholding - tax is positive, you get a refund.No double taxation is happening. Lets say your income before the bonus was X and your tax was Y. Your income after the bonus is X 1000 and your tax will be Y 0.281000 if you are in the middle of the 28 tax bracket, not at a border. In other words, the actual extra tax as a result of the bonus is 280. Only 250 got sent in. Youll settle up at tax time. 