public double GetTax(double income)
{
    var rules = new[] {
        new { Taxable = 0, Rate = 0d },
        new { Taxable = 5070, Rate = 10d },
        new { Taxable = 8660, Rate = 14d },
        new { Taxable = 14070, Rate = 23d },
        new { Taxable = 21240, Rate = 30d },
        new { Taxable = 40230, Rate = 33d },
        new { Taxable = int.MaxValue, Rate = 45d }
    };

    var tax = 0d;
    for (var i = rules.Length - 1; i > 0; i--)
    {
        var taxable = income - rules[i - 1].Taxable;
        if (taxable > 0d)
        {
            tax += taxable * rules[i].Rate / 100d;
            income -= taxable;
        }
    }
    return tax;
}