public Decimal Calculate(int year, decimal annualIncome, EmployeeTaxFilingStatus filingStatus = EmployeeTaxFilingStatus.Single)
{
if (year < TaxTables.Minimum_Year)
{
throw new ArgumentOutOfRangeException("Unable to process tax years before " + TaxTables.Minimum_Year);
}
if (annualIncome < 0)
{
throw new ArgumentOutOfRangeException("AnnualIncome cannot be negative");
}
// Get the appropriate table by year
// Then figure out the correct row based on filing status and income
TaxTableEntry entry = TaxTables
.Values
.Where(t => t.Year == year)
.SelectMany(t => t.Brackets)
.Where(e => e.TaxFilingStatus == filingStatus)
.Where(e => e.Minimum <= annualIncome)
.Where(e => annualIncome < e.Maximum)
.SingleOrDefault();
if (entry == null)
{
throw new ArgumentOutOfRangeException("Unable to find tax table that matches parameters");
}
// Formula is Base amount + the difference between the income and the minimum for the bracket * the percentage in that bracket
return((entry.Base + ((annualIncome - entry.Minimum) * (entry.Percentage / 100))).Round());
}
public Decimal Verify_Withholding(Decimal annualIncome, EmployeeTaxFilingStatus status)
{
return(_calculator.Calculate(YEAR, annualIncome, status));
}
public void Should_Return_No_Withholding_For_Married(
[Values(EmployeeTaxFilingStatus.MarriedFilingJointly, EmployeeTaxFilingStatus.WidowerWithDependentChild)] EmployeeTaxFilingStatus status,
[Random(0, 8450, 5)] Decimal annualIncome)
{
Assert.That(_calculator.Calculate(YEAR, annualIncome, status), Is.EqualTo(0));
}
public void Should_Return_No_Withholding_For_Single(
[Values(EmployeeTaxFilingStatus.Single, EmployeeTaxFilingStatus.MarriedFilingSeparately, EmployeeTaxFilingStatus.HeadOfHousehold)] EmployeeTaxFilingStatus status,
[Random(0, 2250, 5)] Decimal annualIncome)
{
Assert.That(_calculator.Calculate(YEAR, annualIncome, status), Is.EqualTo(0));
}
