The NYPD is on pace to see more than 4,000 officers retire or resign this year – the most since the post-9/11 exodus, data obtained by The New York Post shows.

Pension fund figures reveal 3,054 officers have filed to leave the department so far this year — 42% more than the 2,155 who exited at the same time last year through Sept. 30.

If the pace continues in the fourth quarter, the NYPD stands to lose 4,072 officers this year. That’s even higher than the crippling attrition the department suffered in 2002, when 3,846 officers left the force following Sept. 11, 2001 terrorist attacks on the World Trade Center, where of the city’s finest were killed.

Union leaders warn the mass exits have created a “staffing emergency.”

To get enough personnel on the streets as the force falls to about 34,000 sworn — down from the 40,200 peak in 2000 — the NYPD is on pace to spend $600 million on uniformed staff overtime in the new fiscal year that began in July. That’s 61% percent more than the $372 million budgeted for OT, according to figures from the Independent Budget Office.