Is a static variable shared across all instance?

Question

In a public class, I have a private static Dictionary. Since the Dictionary is static, does it mean that it is shared across all the other instance of the same object (see example below).

public class Tax
{
    private static Dictionary<string, double> TaxBrakets = new Dictionary<string, double>(StringComparer.OrdinalIgnoreCase)
    {
        { "Individual",   0.18 },
        { "Business",     0.20 },
        { "Other",        0.22 },
    };

    public string Type { get; set; }
    public double ComputeTax(string type, double d)
    {
        return d * TaxBrakets[this.Type];
    }
}

Is that acceptable to use a Dictionary in that way (as static variable)?

Answer 1

Your static variable TaxBrakets is not associated with an instance. this.TaxBrakets would not compile. All occurrences of TaxBrakets will refer to the same dictionary. In general, it's totally acceptable to use static dictionaries. This particular use seems a little funny though, but I'd need to see more code to suggest any changes.

Answer 2

Yes, a static variable exists only once in your entire program, I think it will behave the way you expect.

Whether that's the right solution to your accounting problem is debatable, IANAA but my understanding is that tax brackets (note: the correct spelling of "brackets" has a c) equate income levels to marginal tax rates, knowing the type of the entity is not by itself sufficient to determine the tax rate.