Why was so much tax withheld from my bonus?

Your bonus wasn't taxed at a higher rate — it was withheld at a flat supplemental rate, which is different from your actual tax. The IRS lets employers withhold supplemental wages like bonuses at a flat 22% federal rate (37% on amounts over $1 million), plus FICA and state tax. If your true marginal rate is below 22%, you'll get the excess back as a refund; if you're a high earner whose real rate is 32% or more, 22% withholding may actually leave you underwithheld and owing at filing. So the big chunk taken out isn't a penalty — it's just a withholding convention. High earners with large bonuses or RSU vests should check whether 22% covers their real liability and consider extra W-4 withholding to avoid a surprise. Model your true bonus tax at wealthserene.com/tools/w2-optimizer.