What are the advantages of a progressive consumption tax?

A progressive consumption tax would be a good substitute for a progressive income tax because it would produce greater economic efficiencies by promoting investment and savings while eliminating the income tax's disincentivizing of work. Unlike a sales tax imposed at the point of sale, a consumption tax could be structured to be progressive rather than regressive, by using a year end tax return to calculate 'net consumption' during a given tax year, with the return summing all sales of qualified investments and then subtracting all purchases of new qualified investments. The tax return then apply a progressive tax rate to the total net investment. Much of the complexity of the current tax code would be eliminated. There would no longer be a need for complex calculations relating to capital gains, based on the concept of 'tax basis' and other arcane notions. Complexities relating to tax beneficial retirement-related savings accounts would also become unnecessary. Investors would no longer be penalized for efficiency-driven portfolio rebalancing. Billionaires would not be taxed significantly if they live frugally, but they could be taxed at very high rates for substantial consumption. A billionaire who buys large yachts, multiple mega-mansions, etc. would pay high taxes. A billionaire who lives modestly would not. But the latter billionaire is keeping her money invested in the economy, providing resources that will further economic growth. Opponents of a consumption tax cite the fact that most consumption taxes are thought to be regressive. However, as perviously mentioned, the consumption tax could be structured to be progressive, and in fact could be structured to be even more progressive than the current income tax. The progressive rates could be based on wealth rather than the amount of annual consumption or income. It would even be possible to tax consumption at over 100% in the case of billionaires. For example, if someone had a net worth of over $10 billion, we could tax that person's consumption at 150%. Regressiveness concerns can also be addressed by exempting a large portion of consumption. Annual consumption under a certain level, say $30,000 per year, could be tax free, or taxed at a low sales-tax-like rate of, say, 5%. Most economists agree that a consumption tax would promote economic growth.