public ITaxResult TaxFor(decimal payeSalary, decimal privatePension = 0, decimal statePension = 0, RentalIncomeForTax rentalIncome = null)
{
var result = new TaxResult();
AddIncomeTax(payeSalary, privatePension, statePension, rentalIncome, result);
AddNationalInsurance(payeSalary, result);
return(result);
}
private static TaxBands UpdateTaxResultWithIncome(TaxResult result, decimal incomeToCalcTaxOn, IncomeType incomeType, TaxBands taxBands, decimal?incomeToRecord = null, decimal financingCosts = 0)
{
decimal incomeTracker = incomeToCalcTaxOn;
if (incomeToRecord.HasValue && incomeToRecord != incomeToCalcTaxOn)
{
result.AddIncomeFor(incomeToRecord.Value, incomeType);
}
else
{
result.AddIncomeFor(incomeTracker, incomeType);
}
decimal totalTaxPaid = 0;
if (incomeTracker > taxBands.ExtraHighBand)
{
var extraHighBand = (incomeTracker - taxBands.ExtraHighBand) * .45m;
totalTaxPaid += extraHighBand;
result.AddIncomeTax(extraHighBand, incomeType);
incomeTracker = taxBands.ExtraHighBand;
}
if (incomeTracker > taxBands.HigherBand)
{
var higherBandTax = (incomeTracker - taxBands.HigherBand) * .4m;
totalTaxPaid = higherBandTax;
result.AddIncomeTax(higherBandTax, incomeType);
incomeTracker = taxBands.HigherBand;
}
if (incomeTracker > taxBands.PersonalAllowance)
{
var lowerBandTax = (incomeTracker - taxBands.PersonalAllowance) * .2m;
totalTaxPaid += lowerBandTax;
result.AddIncomeTax(lowerBandTax, incomeType);
}
if (IncomeType.RentalIncome == incomeType)
{
var taxCredit = financingCosts * .2m;
var usableTaxCredit = Math.Min(taxCredit, totalTaxPaid);
result.AddRentalTaxCredit(usableTaxCredit);
}
return(taxBands.Subtract(incomeToCalcTaxOn));
}
private static void AddNationalInsurance(decimal payeSalary, TaxResult result)
{
int lowerBound = 9_500;
int midBound = 50_000;
int upperBound = Int32.MaxValue;
if (payeSalary > lowerBound)
{
var lowerRatePay = Math.Min(midBound, payeSalary);
result.AddNationalInsurance(((lowerRatePay - lowerBound) * .12m), IncomeType.Salary);
}
if (payeSalary > midBound)
{
var midRatePay = Math.Min(upperBound, payeSalary);
result.AddNationalInsurance(((midRatePay - midBound) * .02m), IncomeType.Salary);
}
}
private static void AddIncomeTax(decimal payeSalary, decimal privatePension, decimal statePension, RentalIncomeForTax rentalIncome, TaxResult result)
{
var taxBands = TaxBands.InitialEngland2020();
taxBands.UpdatePersonalAllowance(payeSalary, privatePension, statePension, rentalIncome?.GetIncomeToPayTaxOn() ?? 0);
taxBands = UpdateTaxResultWithIncome(result, payeSalary, IncomeType.Salary, taxBands);
taxBands = UpdateTaxResultWithIncome(result, privatePension, IncomeType.PrivatePension, taxBands);
taxBands = UpdateTaxResultWithIncome(result, statePension, IncomeType.StatePension, taxBands);
UpdateTaxResultWithIncome(result, rentalIncome?.GetIncomeToPayTaxOn() ?? 0, IncomeType.RentalIncome, taxBands, rentalIncome?.GetNetIncome(),
rentalIncome?.TaxDeductibleFinancingCosts() ?? 0);
}
