帮忙改一下这个模块？

这个模块是计算工资所得税的，怎样确定缴税基数，请高手给予指点，谢谢

你点模块，把下面内容粘贴进去，然后把它当个函数用
Function tax(paraMoney)
Dim basenum, calcMonay
basenum = 2000
calcMonay = IIf(paraMoney > basenum, paraMoney - basenum, 0)
tax = 0
Select Case calcMonay
    Case Is > 100000:
        tax = calcMonay * 0.45 - 15375
    Case Is >= 80000:
        tax = calcMonay * 0.4 - 10375
    Case Is >= 60000:
        tax = calcMonay * 0.35 - 6375
    Case Is >= 40000:
        tax = calcMonay * 0.3 - 3375
    Case Is >= 20000:
        tax = calcMonay * 0.25 - 1375
    Case Is >= 5000:
        tax = calcMonay * 0.2 - 375
    Case Is >= 2000:
        tax = calcMonay * 0.15 - 125
    Case Is >= 500:
        tax = calcMonay * 0.1 - 25
    Case Is >= 0:
        tax = calcMonay * 0.05 - 0
End Select
End Function

运行时，提示需要输入TAX值