estimated tax return vs declaration of estimated tax

estimated tax return and declaration of estimated tax both are nouns.

Word	Noun	Adjective	Verb	Adverb
estimated tax return	Yes	No	No	No
declaration of estimated tax	Yes	No	No	No

As nouns, estimated tax return and declaration of estimated tax are synonyms defined as:

estimated tax return and declaration of estimated tax: return required of a taxpayer whose tax withheld from income does not meet the tax liability for the year

estimated tax return (noun)	declaration of estimated tax (noun)
return required of a taxpayer whose tax withheld from income does not meet the tax liability for the year	return required of a taxpayer whose tax withheld from income does not meet the tax liability for the year