please explain clearly

Consider a government that imposes a personal income tax. It is estimated that the tax will not affect total labour supplied in the economy. Given this, the political party advocating for the tax argue that the tax acts as a non-distortionary, lump-sum tax, and as such imposes no excess burden. Is this a reasonable argument? The concept of Pareto efficiency is not controversial and is a useful tool to evaluate tax policies. Explain the idea of Pareto efficiency and whether or not you agree with this statement