Date: 201510
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Flight Attendant
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Gate Operations provided both the loadmaster and inflight crew with an inaccurate cabin count. The load sheet with provided numbers indicated 145/1 while the preliminary numbers showed 132.  Upon receiving the load sheet I queried the loadmaster about the abnormal increase in passengers over the preliminary number; as it is unusual for that number to go up.  He reassured me that was the accurate number; I provided the signed release; reported the number to the A flight attendant and we closed up and left per all normal SOP.After climbing out of sterile; the A F/A (Flight Attendant) called and indicated the passenger numbers were wrong.  I told him it was a little late now but what convinced him the numbers were off.  He said we have way more than 5 empty seats; so I looked closer at the gate paperwork and they gave us numbers for a flight from earlier in the day.  I asked him to do an actual count and slide the docs under the door.He performed the actual count it was 124/3.  I reviewed the docs and sure enough Ops had provided both the loadmaster and us with numbers from the wrong flight.  I discussed the situation with the F/O (First Officer) and we both concluded that since we have planned for heavier than we actually are; the performance numbers for the remaining portions of the flight should be faster than required and therefore more conservative and certainly on the safe side of any speed tape or reference speed problems.  Therefore; we made no changes to the FMGC.We did however; ACARS dispatch to inform them of the situation and bring in any additional resources to confirm we were acting in the safest possible manner considering the mistake.  Dispatch confirmed that no changes to ZFW (Zero Fuel Weight) or speeds were necessary to operate in the safest possible manner. The F/O and I decided were acting in the safest course of action and proceeded uneventfully.All ground operations should have some fail safe to make sure they are providing the loadmaster and flight crew with accurate information.  My guess is they do; and this was a case of just not following those procedures.  (ie. reviewing the passenger printout for proper date; flt number and city pair) Additionally; I should have pushed further for an accurate accountability as to why the numbers increased. And any time the gate provides passenger data; I should have reviewed that for accuracy not just the load sheet.  In this case the legal load sheet that I review had the accurate date; flight number etc. It just had a passenger count from inaccurate data.




Synopsis: A319 Captain is informed by the A Flight Attendant airborne; that the passenger count is off by twenty one passengers. The gate agent had provided paper work for a flight that left from the same gate earlier in the day.