If you made $32.05 dollars per hour for 30 hours a week (50K a year) and paid 10% tax on those dollars, you would earn an effective after tax hourly rate of $28.84. If all dollars earned after 50K were then taxed at 15%, your effective after tax hourly rate for working more than 30 hours would be $27.24. A one dollar and six cent reduction. I believe the purpose of time and a half overtime is partly to correct this problem.