Abigail Breslin blindsided her assistant by canning him out of nowhere and stiffing him on his final paycheck ... according to a new suit.
Michael Helms claims he worked as an assistant for the "Scream Queens" actress until she fired him on August 4. Problem is -- he'd already invoiced her for July, but was told he wasn't going to get paid for that month ... according to the docs.
Sources connected to Michael tell us Abigail spoke with him shortly after firing him to find some sort of compromise. We're told her legal team promised they'd be in touch with an offer, but just blew him off ... so Helms filed suit.
He's asking for $3,500 ... which he claims was a month's salary.
We reached out to Breslin's team ... no word back yet.