and wages. Ordinary taxpayers will ultimately pay their taxes from at least one of these revenue sources. The government may intend that a particular tax should fall exclusively on rent, profit, or wages – and that another tax should fall on all three private income sources jointly. However, many taxes will inevitably fall on resources and persons very different from those intended … Good taxes meet four major criteria. They are (1) proportionate to incomes or abilities to pay (2) certain rather than arbitrary (3) payable at times and in ways convenient to the taxpayers and (4) cheap to administer and collect." The side-effects of taxation (such as economic distortions) and theories about how best to tax are an important subject in microeconomics. Taxation is almost never a simple transfer of wealth. Economic theories of taxation approach the question of how to maximize economic welfare through taxation. A 2019 study looking at the impact of tax cuts for different income groups, it was tax cuts for low-income groups that had the greatest positive impact on employment growth. Tax cuts for the wealthiest top 10% had a small impact. Incidence Law establishes from whom a tax is collected. In many countries, taxes are imposed on businesses (such as corporate taxes or portions of payroll taxes). However, who ultimately pays the tax (the tax "burden") is determined by the marketplace as taxes become embedded into production costs. Economic theory suggests that the economic effect of tax does not necessarily fall at the point where it is legally levied. For instance, a tax on employment paid by employers will impact the employee, at least in the long run. The greatest share of the tax burden tends to fall on the most inelastic factor involved—the part of the transaction which is affected least by a change in price. So, for instance, a tax on wages in a town will (at least in the long run) affect property-owners in that area. Depending on how quantities supplied and demanded to vary with price (the "elasticities" of supply and demand), a tax can be absorbed by the seller (in the form of lower pre-tax prices), or by the buyer (in the form of higher post-tax prices). If the elasticity of supply is low, more of the tax will be paid by the supplier. If the elasticity of demand is low, more will be paid by the customer;