尝试开发excel函数来计算CGT (英国)

Function CalculateCGT(purchasePrice As Double, salePrice As Double, purchaseDate As Date, saleDate As Date) As Double
    Dim holdingPeriod As Integer
    Dim taxableGain As Double
    Dim annualExemption As Double
    Dim cgtRate As Double
    
    ' 计算持有期（以年为单位）
    holdingPeriod = Year(saleDate) - Year(purchaseDate)
    
    ' 计算应纳税的利润
    taxableGain = salePrice - purchasePrice
    
    ' 获取当前年度的免税额
    annualExemption = GetAnnualExemption(saleDate)
    
    ' 根据持有期确定适用的税率
    cgtRate = GetCGTRate(holdingPeriod)
    
    ' 计算应缴纳的 CGT
    If taxableGain > annualExemption Then
        CalculateCGT = (taxableGain - annualExemption) * cgtRate
    Else
        CalculateCGT = 0
    End If
End Function

Function GetAnnualExemption(date As Date) As Double
    ' 根据日期获取当前年度的免税额
    ' 这里可以根据实际情况编写代码来获取对应年度的免税额
    ' 例如，可以使用 IF 函数或 VLOOKUP 函数来实现
    ' 返回免税额的数值
End Function

Function GetCGTRate(holdingPeriod As Integer) As Double
    ' 根据持有期确定适用的税率
    ' 这里可以根据实际情况编写代码来获取对应持有期的税率
    ' 例如，可以使用 IF 函数或 VLOOKUP 函数来实现
    ' 返回税率的数值
End Function