income bracket vs income tax bracket

income bracket and income tax bracket both are nouns.

Word	Noun	Adjective	Verb	Adverb
income bracket	Yes	No	No	No
income tax bracket	Yes	No	No	No

As nouns, income bracket and income tax bracket are synonyms defined as:

income bracket and income tax bracket: a category of taxpayers based on the amount of their income

Other synonyms of income bracket include tax bracket.

income bracket (noun)	income tax bracket (noun)
a category of taxpayers based on the amount of their income	a category of taxpayers based on the amount of their income