private static decimal?CalculateTaxableAmountWithinAnnualSalaryTaxBand(
decimal annualSalary,
AnnualSalaryTaxBand annualSalaryTaxBand)
{
if (annualSalary < annualSalaryTaxBand.StartOfRange)
{
return(null);
}
if (annualSalaryTaxBand.EndOfRange == null)
{
return(annualSalary - annualSalaryTaxBand.StartOfRange);
}
decimal endOfTaxableRange;
if (annualSalary < annualSalaryTaxBand.EndOfRange)
{
endOfTaxableRange = annualSalary;
}
else
{
endOfTaxableRange = (decimal)annualSalaryTaxBand.EndOfRange;
}
return(endOfTaxableRange - annualSalaryTaxBand.StartOfRange);
}
private static TaxPayableOnAnnualSalaryTaxBand CalculateTaxPayableForAnnualSalaryTaxBand(
decimal annualSalary,
AnnualSalaryTaxBand annualSalaryTaxBand)
{
var taxableAmount = CalculateTaxableAmountWithinAnnualSalaryTaxBand(
annualSalary,
annualSalaryTaxBand);
if (taxableAmount.HasValue == false)
{
return(new TaxPayableOnAnnualSalaryTaxBand(annualSalaryTaxBand, 0m, 0m));
}
var taxPayable = (decimal)taxableAmount * annualSalaryTaxBand.RateMultiplier;
return(new TaxPayableOnAnnualSalaryTaxBand(
annualSalaryTaxBand,
(decimal)taxableAmount,
taxPayable));
}
