The sitcom's send-off has landed a Friday night 9pm slot, following the series premiere of Marvel's Agents of SHIELD at 8pm.
Series creator Graham Linehan previously announced that the hit comedy's farewell special would air in late September.
Linehan first set out plans for a final IT Crowd special in December 2012, after previously confirming that the sitcom would not return for a full fifth series.
The comedy - which originally aired between 2006 and 2010 - starred Chris O'Dowd, Richard Ayoade and Katherine Parkinson as three staff members of the IT department at the fictional Reynholm Industries.
> IT Crowd Graham Linehan teases new episode with Vine videos - watch
Watch a clip from The IT Crowd below: