tax hike vs tax boost

tax hike and tax boost both are nouns.

Word	Noun	Adjective	Verb	Adverb
tax hike	Yes	No	No	No
tax boost	Yes	No	No	No

As nouns, tax hike and tax boost are synonyms defined as:

Other synonyms of tax hike include tax-increase.

tax hike (noun)	tax boost (noun)
the amount by which taxes are increased	the amount by which taxes are increased