tax return vs income tax return

tax return and income tax return both are nouns.

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

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

tax return and income tax return: document giving the tax collector information about the taxpayer's tax liability

Other synonyms of tax return include return.

tax return (noun)	income tax return (noun)
document giving the tax collector information about the taxpayer's tax liability	document giving the tax collector information about the taxpayer's tax liability