Former City Comptroller John Liu’s state Senate campaign missed the deadline for filing its financial-disclosure statement — and no one there realized it until contacted by The Post Thursday.

Liu’s campaign said it submitted the required paperwork by the July 16 deadline, but didn’t understand that it wasn’t accepted when contacted by the state Board of Elections.

The campaign said it resubmitted the documents Thursday and provided The Post with a copy, which showed Liu has just $984.80 in his kitty.

That gives Liu, who ran for mayor in 2013, another hill to climb in his second primary challenge against Queens Sen. Tony Avella, a former member of the controversial Independent Democratic Conference, who beat him by 568 votes in 2016.