<prompt> Human: My Federal withholding rate is consistently 10.9 of my paycheck. I got a 1000.00 bonus and the Federal withholding was 250.00. Why so high, and why is it a round number? Is there some minimum limit I have to pay?  <response>: A bonus is what the IRS defines as a supplemental wage. Supplemental wages have a flat withholding of 25. 