/ Thesaurus / T Synonyms of tax increase Find synonyms for: Noun1. tax-increase, tax boost, tax hike, increase, incrementusage: the amount by which taxes are increased; "a tax increase of 15 percent"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: aversion Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language