"In terms of taxes, a companies profit = income. Revenue - cost = profit = income."
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Remember, the proposal I was responding to was: "What is needed is to make taxation fair by simply saying that if you get $ from a source, ANY SOURCE, then it will be taxed in the same way with NO BREAKS, DEDUCTIONS, OR EXEMPTIONS."
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Not "income" - "$ from a source, ANY SOURCE," (emphasis windbourne's). And there is the issue of what legitimately counts as a "cost". And in the case of unincorporated sole proprieterships, there is no separation between the person and the business.