Someone else suggested it, and I think it works too - consumption tax on everything (one thing I would add is a scaling tax rate of the per goods cost against the median income, so that a car costing 200k might be taxed 10% higher than a 20k one, and I would call the taxation of large purchases at higher rates a benefit) but a tax credit for everyone equivalent to some metric to measure the amount of money it costs to feed / house / heat / clothe oneself.