Who cares about Domain Rules?

namespace BusinessRules.Evolution_Four
{
    /// <summary>
    /// USA Investor Tax Engine Domain Domain object specific to states tax rules.
    /// </summary>
    internal class UsaIncomeTaxEngine : IncomeTaxEngine
    {
        #region Methods

        /// <summary>
        /// Calculates the tax rate.
        /// </summary>
        /// <returns>
        /// Returns a double representing the tax liability for the investor.
        /// </returns>
        public override Calculation<Investor> CalculateTaxRate()
        {
            return delegate(Investor investor)
                   {
                   double income = investor.Income;

                   if (income >= 0.0 && income <= 7550.99)
                       return 0.10;
                   else if (income >= 7551.00 && income <= 30650.99)
                       return 0.15;
                   else if (income >= 30651.00 && income <= 74200.99)
                       return 0.25;
                   else if (income >= 74201.00 && income <= 154800.99)
                       return 0.28;
                   else if (income >= 154801.00 && income <= 336550.99)
                       return 0.33;
                   else
                       return 0.35;
                   };
        }

        /// <summary>
        /// Calculates the tax liability.
        /// </summary>
        /// <returns>
        /// Returns a double representing the tax rate for the investor.
        /// </returns>
        public override Calculation<Investor> CalculateTaxLiability()
        {
            return delegate(Investor investor)
                   {
                   double taxLiability = 0.0;
                   double income = investor.Income;

                   if (income > 7550.99)
                   {
                       taxLiability += 7550.99 * 0.10;
                   }
                   if (income >= 0.0 && income <= 7550.99)
                   {
                       taxLiability += income * 0.10;
                   }
                   if (income > 30650.99)
                   {
                       taxLiability += (30650.99 - 7551.00) * 0.15;
                   }
                   if (income >= 7551.00 && income <= 30650.99)
                   {
                       taxLiability += (income - 7551.00) * 0.15;
                   }
                   if (income > 74200.99)
                   {
                       taxLiability += (74200.99 - 30651.00) * 0.25;
                   }
                   if (income >= 30651.00 && income <= 74200.99)
                   {
                       taxLiability += (income - 30651.00) * 0.25;
                   }
                   if (income > 154800.99)
                   {
                       taxLiability += (154800.99 - 74201.00) * 0.28;
                   }
                   if (income >= 74201.00 && income <= 154800.99)
                   {
                       taxLiability += (income - 74201.00) * 0.28;
                   }
                   if (income > 336550.99)
                   {
                       taxLiability += (336550.99 - 154801.00) * 0.33;
                   }
                   if (income >= 154801.00 && income <= 336550.99)
                   {
                       taxLiability += (income - 154801.00) * 0.33;
                   }
                   if (income > 336551.00)
                   {
                       taxLiability += (income - 336551.00) * 0.35;
                   }
                   return taxLiability;
                   };
        }

        #endregion
    }
}