Marginal Tax Rate
A company may incur a certain tax rate on income up to a certain amount. Beyond that amount the tax rate may change to the tax rate that is marginal, which then applies to incremental income earned beyond that point.
In the U.S., the marginal tax rate increases as a company’s income increases. So the more a company earns, the higher its tax rate is. Some economists think that this discourages productivity in business.