It's double taxation if two entirely-different entities lay claim to a percentage of pretax income. The same income is being taxed twice. To my thinking, it comes down to the basic division of responsibilities between the Federal, state, and local governments. Simply adding another layer should not require additional tax funding; the question should only be how the income tax an individual pays is distributed between the layers.

Fortunately, that's one advantage to the system we have -- if you don't feel that Sacramento and Washington, DC should both get a crack at your income, you can always move to a state with no income tax. I did.