Original sentence: Because, in the United States, income subject to capital gains tax treatment is excluded from ordinary income taxation by , some argue that it is legally impossible to doubly tax capital gains under that law.Capital gains arise from positive appreciation of assets purchased with after-tax income.The increase in value is what is being taxed, not the after-tax money used to purchase the asset.This increase in value has never been taxed before
Edited sentence: Because in the United States, income subject to capital gains tax treatment is excluded from ordinary income taxation by , some argue that it is legally impossible to doubly tax capital gains under that law.Capital gains arise from positive appreciation of assets paid for with after-tax income.It should be noted in any case that it is the "extra money" earned that is being taxed, not the after-tax money itself used to buy the asset or investment vehicle.This "extra money" has never been taxed before therefore the argument of "double-taxation" is considered absurd by most people