allowable vs permissible

allowable and permissible both are adjectives.

Word	Noun	Adjective	Verb	Adverb
allowable	No	Yes	No	No
permissible	No	Yes	No	No

As adjectives, allowable and permissible are synonyms defined as:

allowable and permissible: that may be permitted especially as according to rule

allowable (adjective)	permissible (adjective)
that may be permitted especially as according to rule	that may be permitted especially as according to rule
deserving to be allowed or considered	that may be accepted or conceded
deductible according to the tax laws