It's all a matter of how much taxes you pay. Lower class pays no taxes because they have little income. Upper class pays little to no taxes because they can afford to invest in the loopholes of the tax system to avoid paying taxes. The middle class is the class that pays the taxes because we have income but not enough to afford the ways to not paying taxes.
So the question you should ask yourself is if you pay any taxes. If you do then you are midlle class otherwise you're not.
