tax-increase vs increment

tax-increase and increment both are nouns.

Word	Noun	Adjective	Verb	Adverb
tax-increase	Yes	No	No	No
increment	Yes	No	No	No

As nouns, increment is a hypernym of tax-increase; that is, increment is a word with a broader meaning than tax-increase:

Other hypernyms of tax-increase include increase.

tax-increase (noun)	increment (noun)
the amount by which taxes are increased	the amount by which something increases
	a process of becoming larger or longer or more numerous or more important