List four ways in which the government's power to tax is limited

The constitution gives the government the power to collect taxes. However, the governments power to tax is limited by four ways which are:
1- Cannot tax exports
2- Must be for general welfare of the population and common defense of the country
3- Prohibits congress from imposing taxes unless divided by population
4- Not for individuals

There were not many poor people in holland who were willing to move.