Abatement of tax

What does Abatement of tax mean in American Law?

The definition of Abatement of tax in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

A decrease in an assessed tax, frequently because of error or illegality in the original taxing process. But the decrease may under many common circumstances be 100% of the tax assessed; hence a tax may be “abated” also in the sense of “voided” or “eliminated.”