Sales tax is highly regressive because poor people spend most of their money staying alive, while rich people can save and reinvest their pre-tax money. You're

Sales tax is highly regressive because poor people spend most of their money staying alive, while rich people can save and reinvest their pre-tax money. You're just reinventing the current de facto regime, where rich people don't pay taxes on investments through "creative" acounting and poor people have their employer deduct their taxes from their income. Realistically you need to have an enforcement agency with some teeth because the wealthiest people can afford to move their own money around and skirt the rules, while poor people will be transacting with third parties that have an interest in collecting and remitting taxes. The grocery store would rather be in compliance with tax law, whether it's sales tax or income tax, but your private investment office doesn't have the same incentives.