个税起征点：3500元(国内) ; 4800(国外)
税前计算税后工资
=ROUND(MAX((A1-3500)*5%*{0.6,2,4,5,6,7,9}-5*{0,21,111,201,551,1101,2701},0),2)
税后计算税前工资
=ROUND(MAX((A1-3500-{0,105,555,1005,2755,5505,13505})/(1-{0.03,0.1,0.2,0.25,0.3,0.35,0.45})+3500,A1),2)
税前计算个税：
=MAX((应纳税所得-3500)*{0.03,0.1,0.2,0.25,0.3,0.35,0.45}-{0,105,555,1005,2755,5505,13505},0)
个税反推税前：
=MIN((税额 +{0,105,555,1005,2755,5505,13505})/({0.03,0.1,0.2,0.25,0.3,0.35,0.45})+3500)
