ConcreteTaxCalculators.cs

public class TaxCalculator1 : TaxCalculator
{
    protected override bool CanCalculateExpenses => false;
    protected override bool CanCalculateIncomeTax => true;
    protected override bool CanCalculateVat => false;


    // No logic to apply. Therefore, just return 0.
    protected override decimal CalculateExpenses(decimal input)
    {
        return 0;
    }

    protected override decimal CalculateIncomeTax(decimal income)
    {
        return income + 100;
    }

    // No logic to apply. Therefore, just return 0.
    protected override decimal CalculateVat(decimal vat)
    {
        return 0;
    }
}

public class TaxCalculator2 : TaxCalculator
{
    protected override bool CanCalculateExpenses => true;
    protected override bool CanCalculateIncomeTax => false;
    protected override bool CanCalculateVat => false;


    protected override decimal CalculateExpenses(decimal input)
    {
        return input + 120;
    }

    // No logic to apply. Therefore, just return 0.
    protected override decimal CalculateIncomeTax(decimal income)
    {
        return 0;
    }

    // No logic to apply. Therefore, just return 0.
    protected override decimal CalculateVat(decimal vat)
    {
        return 0;
    }
}