去年年终奖比前年涨了一些，但实际到手反而少了，当时只知道是因为税率提了一档导致的，但没有深究为什么
最近研究了一下，发现这就是著名的年终奖一元陷阱
年终奖的税率计算是，先把年终奖平分到12个月，根据个人所得税税率表找到对应的税率
于是年终奖扣税 = 年终奖×对应税率 - 速算扣除数
如果年终奖多了1块钱，进入下一档税率，根据跨度，会多扣5到15个点，但对应的速扣数没有增加12倍，就导致了年终奖多发一元，实际到手少很多的年终奖一元陷阱
举例说明，假如13薪和年终奖一起发，两个加一起算总年终奖。
比如13薪是10000，年终奖44000，总年终奖是54000，得出54000/12 = 1500， 查表得出用10%那档税率， 实际到手 = 54000 - (54000 × 10% - 105) = 48705
假如年终奖涨了1000，总年终奖变成55000，55000/12 = 4583， 查表得出用20% 那档税率， 实际到手 = 55000 - (55000 × 20% - 555) =44555
税率档从10%升到20%，所以虽然总年终奖多了1000，但扣的税多了5150，导致实际到手反而少了4150
代码如下
def taxRate(bonus,thirteen_month_salary): total = bonus + thirteen_month_salary base = total/12 if base < 0: bonus_tax = 0 if base <= 1500: bonus_tax = total * 0.03 elif base > 1500 and base <= 4500: bonus_tax = total * 0.1 - 105 elif base > 4500 and base <= 9000: bonus_tax = total * 0.2 - 555 elif base > 9000 and base <= 35000: bonus_tax = total * 0.25 - 1005 elif base > 35000 and base <= 55000: bonus_tax = total * 0.3 - 2755 elif base > 55000 and base <= 80000: bonus_tax = total * 0.35 - 5505 elif base > 80000: bonus_tax = total * 0.45 - 13505 print('Bonus tax payable is : %d' % bonus_tax) return bonus_tax def BonusAfterTax(bonus, thirteen_month_salary): # 纳税额 tax = taxRate(bonus,thirteen_month_salary) # 税后bonus bonus_after_tax = bonus + thirteen_month_salary - tax print('Bonus after tax is : %d' % bonus_after_tax) print('bonus_after_tax percentage is : %.2f %%' % float(bonus_after_tax * 100 / (bonus + thirteen_month_salary))) return bonus_after_tax if __name__ == '__main__': bonus_before_tax = int(input('Please input your Bonus before tax:')) thirteen_month_salary = int(input('Please input your 13rd Salary before tax:')) BonusAfterTax(bonus_before_tax, thirteen_month_salary)
如果速扣数也能对应增加12倍，年终奖一元陷阱就解决了
同样总年终奖从54000涨到55000，如果速扣数相应增加12倍，得出税后年终奖从49860涨到50660
这样税前年终奖涨1000，实际到手涨800，而不是少4150，这才符合期望
期待税法能早点把这个失误改过来
代码如下
def bonusTaxRate(bonus,thirteen_month_salary): total = bonus + thirteen_month_salary base = total/12 if base < 0: bonus_tax = 0 if base <= 1500: bonus_tax = total * 0.03 elif base > 1500 and base <= 4500: bonus_tax = total * 0.1 - 105 elif base > 4500 and base <= 9000: bonus_tax = total * 0.2 - 555 elif base > 9000 and base <= 35000: bonus_tax = total * 0.25 - 1005 elif base > 35000 and base <= 55000: bonus_tax = total * 0.3 - 2755 elif base > 55000 and base <= 80000: bonus_tax = total * 0.35 - 5505 elif base > 80000: bonus_tax = total * 0.45 - 13505 print('Bonus tax payable is : %d' % bonus_tax) return bonus_tax def bonusAfterTax(bonus, thirteen_month_salary): # 纳税额 tax = bonusTaxRate(bonus,thirteen_month_salary) # 税后bonus bonus_after_tax = bonus + thirteen_month_salary - tax print('Bonus after tax is : %d' % bonus_after_tax) print('bonus_after_tax percentage is : %.2f %%' % float(bonus_after_tax * 100 / (bonus + thirteen_month_salary))) print(' ') return bonus_after_tax def newBonusTaxRate(bonus, thirteen_month_salary): total = bonus + thirteen_month_salary base = total / 12 #速扣数相应增大12倍 if base < 0: bonus_tax = 0 if base <= 1500: bonus_tax = total * 0.03 elif base > 1500 and base <= 4500: bonus_tax = total * 0.1 - 105 * 12 elif base > 4500 and base <= 9000: bonus_tax = total * 0.2 - 555 * 12 elif base > 9000 and base <= 35000: bonus_tax = total * 0.25 - 1005 * 12 elif base > 35000 and base <= 55000: bonus_tax = total * 0.3 - 2755 * 12 elif base > 55000 and base <= 80000: bonus_tax = total * 0.35 - 5505 * 12 elif base > 80000: bonus_tax = total * 0.45 - 13505 * 12 print('New bonus tax payable is : %d' % bonus_tax) return bonus_tax def newBonusAfterTax(bonus, thirteen_month_salary): total = bonus + thirteen_month_salary # 纳税额 new_bonus_tax = newBonusTaxRate(bonus,thirteen_month_salary) # 税后bonus bonus_after_tax = total - new_bonus_tax print('New Bonus after tax is : %d' % bonus_after_tax) print('New bonus_after_tax percentage is : %.2f %%' % float(bonus_after_tax * 100 / total)) print(' ') return bonus_after_tax if __name__ == '__main__': bonus_before_tax = int(input('Please input your Bonus before tax:')) thirteen_month_salary = int(input('Please input your 13rd Salary before tax:')) bonusAfterTax(bonus_before_tax, thirteen_month_salary) newBonusAfterTax(bonus_before_tax, thirteen_month_salary)
