[Excel] Tạo hàm tính thuế thu nhập cá nhân bằng VBA

Option Explicit
Public Function THUETHUNHAP(LUONG As Double, GIAMTRU As Byte) As Double
	'Khai bao bien
	Dim TIENTHUE As Double
	Dim CHIUTHUE As Double
	'Tinh thue
	CHIUTHUE = LUONG - (11000000 + (GIAMTRU * 4400000))
	If CHIUTHUE <= 0 Then
	TIENTHUE = 0
	ElseIf CHIUTHUE <= 5000000 Then
	TIENTHUE = CHIUTHUE * 0.05
	ElseIf CHIUTHUE <= 10000000 Then
	TIENTHUE = 250000 + ((CHIUTHUE - 5000000) * 0.1)
	ElseIf CHIUTHUE <= 18000000 Then
	TIENTHUE = 750000 + ((CHIUTHUE - 10000000) * 0.15)
	ElseIf CHIUTHUE <= 32000000 Then
	TIENTHUE = 1950000 + ((CHIUTHUE - 18000000) * 0.2)
	ElseIf CHIUTHUE <= 52000000 Then
	TIENTHUE = 4750000 + ((CHIUTHUE - 32000000) * 0.25)
	ElseIf CHIUTHUE <= 80000000 Then
	TIENTHUE = 9750000 + ((CHIUTHUE - 52000000) * 0.3)
	Else:
	TIENTHUE = 18150000 + ((CHIUTHUE - 80000000) * 0.35)
	End If
	'Tra ve
	THUETHUNHAP = TIENTHUE
End Function